Detecting chronic kidney disease in population-based administrative databases using an algorithm of hospital encounter and physician claim codes

Approaches for the identification of chronic kidney disease in CPRD-HES-linked studies

Aim: There are different methods to identify chronic kidney disease (CKD) in Clinical Practice Research Datalink (CPRD)-Hospital Episode Statistics (HES). Methods: Using CPRD-HES, nonvalvular atrial fibrillation patients were classified according to CKD category. Results: Using glomerular filtration rate/estimated glomerular filtration rate tests only to identify patients with CKD resulted in 3.5% stage 2, 2.7% stage 3, 0.3% stage 4 and 0.03% stage 5. Using data from diagnostic codes to identify patients with CKD resulted in 1.4% stage 3, 0.4% stage 4 and 0.3% stage 5. Using test records and codes resulted in 3.5% stage 2, 4.0% stage 3, 0.6% stage 4 and 0.4% stage 5. Conclusion: To identify CKD status in CPRD-HES, a combination of test records and codes should be used. Using diagnostic codes only significantly underestimates CKD prevalence.

The risk of deliberate self-harm following a diagnosis of rheumatoid arthritis or ankylosing spondylitis: A population-based cohort study

Objective

Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) are associated with mental illness. The risk of serious mental illness, including deliberate self-harm (DSH), in these conditions is not well known. We aimed to determine if RA or AS independently increases the risk for DSH.

Methods

We conducted retrospective, population-based cohort studies using administrative health data for the province of Ontario, Canada between April 1, 2002 and March 31, 2014. Individuals with incident RA (N = 53,240) or AS (N = 13,964) were separately matched 1:4 by age, sex, and year with comparators without RA or AS. The outcome was a first DSH attempt identified using emergency department data. We estimated hazard ratios (HR) and 95% confidence intervals (95% CI) for risk of DSH in RA and AS versus comparators, adjusting for demographic, clinical and health service utilization variables.

Results

Subjects with AS were significantly more likely to self-harm (crude incidence rate [IR] of 0.68/1,000 person years [PY] versus 0.32/1,000 PY in comparators), with an adjusted HR of 1.59 (95% CI 1.15 to 2.21). DSH was increased for RA subjects (IR 0.35/1,000 PY) versus comparators (IR 0.24/1,000 PY) only before (HR 1.43, 95% CI 1.16 to 1.74), but not after covariate adjustment (HR 1.07, 95% CI 0.86 to 1.33).

Conclusions

AS carries an increased risk for DSH but no such risk was observed in RA. Further evaluation of at-risk AS subjects is needed, including the longitudinal effects of disease and arthritis therapies on self-harm behaviour. This will inform whether specific risk-reduction strategies for DSH in inflammatory arthritis are needed.

Adapting electronic health records-derived phenotypes to claims data: Lessons learned in using limited clinical data for phenotyping

Algorithms for identifying patients of interest from observational data must address missing and inaccurate data and are desired to achieve comparable performance on both administrative claims and electronic health records data. However, administrative claims data do not contain the necessary information to develop accurate algorithms for disorders that require laboratory results, and this omission can result in insensitive diagnostic code-based algorithms. In this paper, we tested our assertion that the performance of a diagnosis code-based algorithm for chronic kidney disorder (CKD) can be improved by adding other codes indirectly related to CKD (e.g., codes for dialysis, kidney transplant, suspicious kidney disorders). Following the best practices from Observational Health Data Sciences and Informatics (OHDSI), we adapted an electronic health record-based gold standard algorithm for CKD and then created algorithms that can be executed on administrative claims data and account for related data quality issues. We externally validated our algorithms on four electronic health record datasets in the OHDSI network. Compared to the algorithm that uses CKD diagnostic codes only, positive predictive value of the algorithms that use additional codes was slightly increased (47.4% vs. 47.9-48.5% respectively). The algorithms adapted from the gold standard algorithm can be used to infer chronic kidney disorder based on administrative claims data. We succeeded in improving the generalizability and consistency of the CKD phenotypes by using data and vocabulary standardized across the OHDSI network, although performance variability across datasets remains. We showed that identifying and addressing coding and data heterogeneity can improve the performance of the algorithms.

Evaluating Quality Metrics and Cost After Discharge: A Population-based Cohort Study of Value in Health Care Following Elective Major Vascular Surgery

BACKGROUND

Early readmission to hospital after surgery is an omnipresent quality metric across surgical fields. We sought to understand the relative importance of hospital readmission among all health services received after hospital discharge.

OBJECTIVE

The aim of this study was to characterize 30-day postdischarge cost and risk of an emergency department (ED) visit, readmission, or death after hospitalization for elective major vascular surgery.

METHODS

This is a population-based retrospective cohort study of patients who underwent elective major vascular surgery - carotid endarterectomy, EVAR, open AAA repair, bypass for lower extremity peripheral arterial disease - in Ontario, Canada, between 2004 and 2015. The outcomes of interest included quality metrics - ED visit, readmission, death - and cost to the Ministry of Health, within 30 days of discharge. Costs after discharge included those attributable to hospital readmission, ED visits, rehab, physician billing, outpatient nursing and allied health care, medications, interventions, and tests. Multivariable regression models characterized the association of pre-discharge characteristics with the above-mentioned postdischarge quality metrics and cost.

RESULTS

A total of 30,752 patients were identified. Within 30 days of discharge, 2588 (8.4%) patients were readmitted to hospital and 13 patients died (0.04%). Another 4145 (13.5%) patients visited an ED without requiring admission. Across all patients, over half of 30-day postdischarge costs were attributable to outpatient care. Patients at an increased risk of an ED visit, readmission, or death within 30 days of discharge differed from those patients with relatively higher 30-day costs.

CONCLUSION

Events occurring outside the hospital setting should be integral to the evaluation of quality of care and cost after hospitalization for major vascular surgery.

Prescribing Patterns for Treatment of Mycobacterium avium Complex and M. xenopi Pulmonary Disease in Ontario, Canada, 2001-2013

Surveys suggest that clinicians diverge from guidelines when treating Mycobacterium avium complex (MAC) pulmonary disease (PD). To determine prescribing patterns, we conducted a cohort study of adults >66 years of age in Ontario, Canada, with MAC or Mycobacterium xenopi PD during 2001-2013. Using linked laboratory and health administrative databases, we studied the first treatment episode (>60 continuous days of >1 of a macrolide, ethambutol, rifamycin, fluoroquinolone, linezolid, inhaled amikacin, or, for M. xenopi, isoniazid). Treatment was prescribed for 24% MAC and 15% of M. xenopi PD patients. Most commonly prescribed was the recommended combination of macrolide, ethambutol, and rifamycin, for 47% of MAC and 36% of M. xenopi PD patients. Among MAC PD patients, 20% received macrolide monotherapy and 33% received regimens associated with emergent macrolide resistance. Although the most commonly prescribed regimen was guidelines-recommended, many regimens prescribed for MAC PD were associated with emergent macrolide resistance.

Determining the Time of Cancer Recurrence Using Claims or Electronic Medical Record Data

PURPOSE

Data from claims and electronic medical records (EMRs) are frequently used to identify clinical events (eg, cancer diagnosis, stroke). However, accurately determining the time of clinical events can be challenging, and the methods used to generate time estimates are underdeveloped. We sought to develop an approach to determine the time of a clinical event-cancer recurrence-using high-dimensional longitudinal structured data.

METHODS

Manual chart abstraction provided information regarding the actual time of cancer recurrence. These data were linked to claims from Medicare or structured EMR data from the Cancer Research Network, which were used to determine time of recurrence for patients with lung or colorectal cancer. We analyzed the longitudinal profile of codes that could help determine the time of recurrence, adjusted for systematic differences between code dates and recurrence dates, and integrated time estimates from different codes to empirically derive an optimal algorithm.

RESULTS

We identified twelve code groups that could help determine the time of recurrence. Using claims data for patients with lung cancer, the optimal algorithm consisted of three code groups and provided an average prediction error of 4.8 months. Using EMR data or applying this approach to patients with colorectal cancer yielded similar results.

CONCLUSION

Time estimates were improved by selecting codes not necessarily the same as those used to identify recurrence, combining time estimates from multiple code groups, and adjusting for systematic bias between code dates and recurrence dates. Improving the accuracy of time estimates for clinical events can facilitate research, quality measurement, and process improvement.

Acute Kidney Injury in Critically Ill Children and Subsequent Chronic Kidney Disease

BACKGROUND

The progression from acute kidney injury (AKI) to chronic kidney disease (CKD) is not well understood in children.

OBJECTIVES

We aimed to develop a pediatric CKD definition using administrative data and use it to evaluate the association between AKI in critically ill children and CKD 5 years after hospital discharge.

DESIGN

Retrospective cohort study using chart collection and administrative data.

SETTING

Two-center study in Montreal, Canada.

PATIENTS

Children (≤18 years old) admitted to two pediatric intensive care units (ICUs) between 2003 and 2005. We a priori excluded patients with end-stage renal disease or no health care number. Only the first admission during the study period was included. We excluded patients who could not be linked to administrative data, did not survive hospitalization, or had preexisting renal disease.

MEASUREMENTS

Acute kidney injury was defined using Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Patients were defined as having CKD 5 years post-discharge if they had ≥1 CKD diagnostic code or ≥1 CKD-specific medication prescription.

METHODS

Chart data used to define the exposure (AKI) were merged with provincial administrative data used to define the outcome (CKD). Cox regression was used to evaluate the AKI-CKD association.

RESULTS

A total of 2235 (56% male) patients were included, and the median admission age was 3.7 years. A total of 464 (21%) patients developed AKI during pediatric ICU admission. At 5 years post-discharge, 43 (2%) patients had a CKD diagnosis. Patients with both stage 1 and stage 2-3 AKI had increased risk of a CKD diagnosis, with the adjusted hazard ratios (95% confidence intervals) of 2.2 (1.1-4.5) and 2.5 (1.1-5.7), respectively (P < .001).

LIMITATIONS

Results may not be generalizable to non-ICU patients. We were not able to control for post-discharge variables; future research should try to explore these additional potential risk factors further.

CONCLUSIONS

Acute kidney injury is associated with 5-year post-discharge CKD diagnosis defined by administrative health care data.

Association of Early-Stage Breast Cancer and Subsequent Chemotherapy With Risk of Atrial Fibrillation

IMPORTANCE

Several types of cancer have been linked to a higher risk of developing atrial fibrillation (AF). Fewer data exist regarding early-stage breast cancer (EBC), for which cardio-oncology concerns are more pertinent.

OBJECTIVE

To investigate the association of EBC and subsequent chemotherapy with the risk of developing AF.

DESIGN, SETTING, AND PARTICIPANTS

This was a population-based, retrospective, matched cohort study conducted in Toronto, Ontario, Canada, of 68 113 women diagnosed with EBC between April 2007 and December 2016 who were matched 1:3 to a cancer-free control group based on birth year and receipt of breast imaging. Prevalence of AF before the index date (date of EBC diagnosis) was compared between the cohorts using the McNemar test. Cumulative incidence function curves were used to describe the AF incidence. To study preexisting AF, participants were matched before exclusion for prior AF. For the remaining analyses, we excluded women with prior AF before matching. An analysis was conducted beginning 1 year after the index date (ie, excluding AF diagnoses in year 1), which we stratified by chemotherapy exposure. Multivariable cause-specific regression was used to determine the hazard ratio (HR) associated with EBC relative to the controls and the association of chemotherapy with AF in patients with EBC.

EXPOSURES

Breast cancer and chemotherapy.

MAIN OUTCOMES AND MEASURES

Incidence of AF.

RESULTS

A total of 68 113 women with EBC and 204 330 cancer-free controls were included in the study; both groups had a mean (SD) age of 60 (13) years. Of the women with EBC, 44.3% were diagnosed as having stage I breast cancer; 38.7%, stage II; and 13.4%, stage III; cancer stage information was missing for 3.6% of the patients. No difference was observed in preexisting AF prevalence (5.3% in the EBC cohort vs 5.2% in controls; P = .21). At 10 years after the index date, the AF incidence was 7.4% (95% CI, 7.1%-7.7%) for women with EBC and 6.8% (95% CI, 6.7%-7.0%) for the controls (P < .001). The adjusted cause-specific HR was significantly elevated at year 1 (HR, 2.16; 95% CI, 1.94-2.41) and after year 5 (HR, 1.20; 95% CI, 1.11-1.30) but not during years 2 through 5. Analyses beginning 1 year after diagnosis showed attenuated differences that remained statistically significant: the cumulative incidence of AF at 9-year follow-up was 7.0% (95% CI, 6.7%-7.3%) for patients with EBC and 6.5% (95% CI, 6.3%-6.7%) for the cancer-free controls. The rate of AF was higher in women who received chemotherapy (adjusted HR, 1.23; 95% CI, 1.13-1.35) but was not associated with exposure to anthracyclines or trastuzumab.

CONCLUSIONS AND RELEVANCE

This study's findings suggest that patients with EBC may not have a higher prevalence of AF before cancer diagnosis. A higher rate of AF was observed in the first year and after 5 years following the EBC diagnosis. The rate of AF was higher in patients who received chemotherapy but appeared to not be associated with specific cardiotoxic agents. These findings suggest that the early and late periods of increased AF risk in EBC survivors warrant focused research to better understand the underlying causes and subsequent implications.

Association between intravenous contrast media exposure and non-recovery from dialysis-requiring septic acute kidney injury: a nationwide observational study

PURPOSE

This study aimed to examine the association between the use of intravenous contrast and non-recovery from dialysis-requiring acute kidney injury (AKI-D) and in-hospital mortality among patients with sepsis.

METHODS

This was a retrospective observational study using the Japanese Diagnosis Procedure Combination inpatient database between January 2011 and December 2016. We identified patients with septic AKI who began continuous renal replacement therapy (RRT) within 2-days of admission and underwent computed tomography. We compared patients with AKI-D with and without the use of intravenous contrast for computed tomography and performed propensity score matching to adjust for confounders for the association between exposure to intravenous contrast and outcomes, including a composite outcome of in-hospital mortality and RRT dependence at discharge and RRT duration.

RESULTS

From 3782 and 6619 patients with septic AKI-D with and without intravenous contrast exposure, respectively, 3485 propensity score-matched pairs were generated. No significant differences were found in the outcomes between the propensity score-matched groups: a composite outcome of in-hospital mortality and RRT dependence, 49.6% vs. 50.2% (odds ratio (OR) 0.98; 95% CI (confidence interval) 0.88, 1.07); in-hospital mortality, 45.3% vs. 46.1% (OR 0.97; 95% CI 0.87, 1.06); RRT dependence, 4.4% vs 4.1% (OR 1.08; 95% CI 0.85, 1.31); and median (interquartile range) of RRT duration, 4 [2-11] days vs. 4 [2-11] days (P = 0.58).

CONCLUSIONS

This large observational study did not support an association between intravenous contrast media and adverse in-hospital outcomes in patients with septic AKI-D. Further studies are warranted to assess the generalizability.

Importance of Considering Competing Risks in Time-to-Event Analyses: Application to Stroke Risk in a Retrospective Cohort Study of Elderly Patients With Atrial Fibrillation

Supplemental Digital Content is available in the text.

Background:

Ignoring competing risks in time-to-event analyses can lead to biased risk estimates, particularly for elderly patients with multimorbidity. We aimed to demonstrate the impact of considering competing risks when estimating the cumulative incidence and risk of stroke among elderly atrial fibrillation patients.

Methods and Results:

Using linked administrative databases, we identified patients with atrial fibrillation aged ≥66 years discharged from hospital in ON, Canada between January 1, 2007, and March 31, 2011. We estimated the cumulative incidence of stroke hospitalization using the complement of the Kaplan–Meier function and the cumulative incidence function. This was repeated after stratifying the cohort by presence of prespecified comorbidities: chronic kidney disease, chronic obstructive pulmonary disease, cancer, or dementia. The full cohort was used to regress components of the CHA₂DS₂VASc (congestive heart failure, hypertension, age, diabetes mellitus, stroke, vascular disease, sex) score on the hazard of stroke hospitalization using the Fine-Gray and Cox methods. These models were subsequently used to predict the 5-year risk of stroke hospitalization. Among 136 156 patients, the median CHA₂DS₂VASc score was 4 and 84 728 patients (62.2%) had ≥1 prespecified comorbidity. The 5-year cumulative incidence of stroke was 5.4% (95% confidence interval, 5.3%–5.5%), whereas that of death without stroke was 48.8% (95% confidence interval, 48.5%–49.1%). The incidence of both events was overestimated by the Kaplan–Meier method; stroke incidence was overestimated by a relative factor of 39%. The degree of overestimation was larger among patients with non-CHA₂DS₂VASc comorbidity because of higher incidence of death without stroke. The Fine-Gray model demonstrated better calibration than the Cox model, which consistently overpredicted stroke incidence.

Conclusions:

The incidence of death without stroke was 9-fold higher than that of stroke, leading to biased estimates of stroke risk with traditional time-to-event methods. Statistical methods that appropriately account for competing risks should be used to mitigate this bias.

Trends in Quality of Care for Patients with CKD in the United States

BACKGROUND AND OBJECTIVES

Improving the quality of CKD care has important public health implications to delay disease progression and prevent ESKD. National trends of the quality of CKD care are not well established. Furthermore, it is unknown whether gaps in quality of care are due to lack of physician awareness of CKD status of patients or other factors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a national, serial, cross-sectional study of visits to office-based ambulatory care practices for adults with diagnosed CKD from the years 2006 to 2014. We assessed the following quality indicators: (1) BP measurement, (2) uncontrolled hypertension, (3) uncontrolled diabetes, (4) angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use among patients with hypertension, (5) statin use if age ≥50 years old, and (6) nonsteroidal anti-inflammatory drug use. Using multivariable linear regression and chi-squared analysis, we examined the change in quality performance over time.

RESULTS

Between 2006 and 2014, there were 7099 unweighted visits for patients with CKD representing 186,961,565 weighted visits. There was no difference in the prevalence of uncontrolled hypertension (>130/80 mm Hg) over time (46% in 2006-2008 versus 48% in 2012-2014; P=0.50). There was a high prevalence of uncontrolled diabetes in 2012-2014 (40% for hemoglobin A1c >7%). The prevalence of ACEi/ARB use decreased from 45% in 2006-2008 to 36% in 2012-2014, which did not reach statistical significance (P=0.07). Statin use in patients with CKD who were 50 years or older was low and remained unchanged from 29% in 2006-2008 to 31% in 2012-2014 (P=0.92).

CONCLUSIONS

In a nationally representative dataset, we found that patients with CKD had a high prevalence of uncontrolled hypertension and diabetes and a low use of statins that did not improve over time and was not concordant with guidelines.

Can billing codes accurately identify rapidly progressing stage 3 and stage 4 chronic kidney disease patients: a diagnostic test study

Background

The International Classification of Diseases (ICD) coding system is the industry standard tool for billing, disease classification, and epidemiology purposes. However, ICD codes are often not assigned or incorrectly given, particularly among Chronic Kidney disease (CKD) patients. Our study evaluated the diagnostic accuracy of CKD-staging ICD codes among CKD patients from a large insurer database in identifying individuals rapidly progressing towards end-stage renal disease (ESRD).

Patients and methods

Serial observations including outpatient serum creatinine measurements collected from 2007 through 2014 of 216,529 patients were examined. The progression of CKD using a serum creatinine based longitudinal mixed-model was contrasted with that documented by CKD-staging ICD codes. Rapid progressors, defined as those with yearly estimated glomerular filtration rate (eGFR) loss greater than 4 ml/min/1.73m²) were identified. The diagnosis of CKD using eGFR was also compared to diagnosis using a set of CKD related ICD codes.

Results

Of 10,927 clinically identified CKD patients qualifying for inclusion in the progression analysis, 323 were clinically identified as rapid progressors. CKD-staging ICD codes identified 83 of these, for a sensitivity of 25.7% with positive predictive value (PPV) of 13.74%, and specificity 95.09% with negative predictive value (NPV) of 97.68%. Of 28,762 laboratory-confirmed CKD patients, 9249 had a qualifying ICD code, for a sensitivity of 16% with PPV of 63.10%; Of 187,767 patients with laboratory-confirmed absence of CKD, 182,359 also did not have a qualifying ICD code, for a specificity of 97.12% with NPV of 90.33%.

Conclusion

This study depicts the novel finding that ICD-codes display poor capacity to identify rapidly progressing CKD patients when compared to gold standard eGFR measures, and further demonstrates the limitations of coding in CKD diagnosis. This analysis further defines the limitations of ICD codes in addressing diagnosis of disease severity or disease progression for clinical or epidemiological purposes.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1429-4) contains supplementary material, which is available to authorized users.

Temporal change in characteristics and outcomes of acute kidney injury on renal replacement therapy in intensive care units: analysis of a nationwide administrative database in Japan, 2007-2016

Background

We aimed to examine recent trends in patient characteristics and mortality in patients with acute kidney injury (AKI) receiving renal replacement therapy (RRT), including continuous RRT (CRRT) and intermittent RRT (IRRT), in intensive care units (ICUs).

Methods

From the Diagnosis Procedure Combination database in Japan during 6 months (July–December) from 2007 to 2016, we identified patients with AKI who received RRT in ICUs. We restricted the study participants to those admitted to hospitals (in which both CRRT and IRRT were available) that participated in the Diagnosis Procedure Combination database for all 10 years. We examined the trends in patient characteristics and mortality overall, by RRT modality, and by main diagnosis category subgroup. Logistic regression was used to adjust for patient characteristics.

Results

We identified 51,758 patients starting RRT in 287 hospitals, including 39,471 (76.3%) and 12,287 (23.7%) patients starting CRRT and IRRT. The crude in-hospital mortality declined from 44.9 to 36.1% (P for trend < 0.001). Compared with 2007, the adjusted odds ratio (aOR) for in-hospital mortality was 0.66 (95% confidence interval (CI) 0.60–0.72) in 2016, and the decreasing trend was observed in both patients starting CRRT (aOR 0.67, 95% CI 0.61–0.75) and IRRT (0.58, 0.45–0.74), and in all subgroups except for coronary artery disease: sepsis aOR 0.68 (95% CI 0.57–0.81); cardiovascular surgery 0.58 (0.45–0.76); coronary artery disease 0.84 (0.60–1.19); non-coronary heart disease 0.78 (0.64–0.94); central nervous system disorders 0.42 (0.28–0.62); trauma 0.39 (0.21–0.72); and other 0.64 (0.50–0.82).

Conclusions

This nationwide study confirmed a consistent decline in mortality among patients with AKI on RRT in ICUs. The adjusted mortality also declined during the study period; however, physiological variables were not measured in this study and it is possible that RRT may have been indicated for patients with less severe AKI in more recent years.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2468-8) contains supplementary material, which is available to authorized users.

Sickle cell trait and renal disease among African American U.S. Army soldiers

Sickle cell trait and certain renal disorders are disproportionately prevalent among African American individuals, so a clear understanding of their association is important. We conducted a longitudinal study using the Stanford Military Data Repository to examine sickle cell trait in relation to the incidence of acute kidney injury (AKI) and chronic kidney disease (CKD). Our study population consisted of African American U.S. Army soldiers on active duty between January 2011 and December 2014. The cumulative incidence was 0·51% for AKI (236 cases out of 45 901 soldiers) and 0·56% for CKD (255 cases out of 45 882 soldiers). Discrete time logistic regression models adjusting for demographic-, military- and healthcare-related covariates showed that sickle cell trait was associated with significantly higher adjusted odds of both AKI [odds ratio (OR): 1·74; 95% confidence interval (CI): 1·17-2·59] and CKD (OR: 2·00; 95% CI: 1·39-2·88). Elevated odds of AKI and CKD were also observed in association with prior CKD and AKI, respectively, and with obesity and prior hypertension. Individuals with sickle cell trait and their providers should be aware of the possibility of increased risk of AKI and CKD to allow for timely intervention and possible prevention.

Impact of Socioeconomic Status on Incidence of End-Stage Renal Disease and Mortality After Dialysis in Adults With Diabetes

OBJECTIVES

To determine whether low socioeconomic status (SES), with or without universal drug coverage, predicts end-stage renal disease (ESRD) and survival after dialysis in patients with diabetes.

METHODS

We conducted a population-based retrospective cohort study in Ontario, Canada. We used ≥65 years of age as a surrogate for universal drug coverage. Adults with diabetes were followed from March 31, 1997 to March 31, 2011 for occurrence of the composite primary outcome (acute kidney injury, ESRD requiring dialysis or kidney transplantation). Patients on dialysis with diabetes were followed from April 1, 1994 to March 31, 2011 for occurrence of death or transplantation.

RESULTS

SES quintile (Q) was inversely associated with the primary outcome in both age groups; however, the gradient was higher in those <65 years of age (Q1:Q5 hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.37-1.49) compared with ≥65 years of age (HR, 1.19; 95% CI, 1.15-1.24). Low SES was associated with a lower likelihood of kidney transplantation among those <65 years of age (HR, 0.77; 95% CI, 0.65-0.92). In patients on dialysis, low SES was associated with higher mortality (HR, 1.09; 95% CI, 1.02-1.16) in both age groups. This association was eliminated after accounting for the decreased rates of kidney transplantation in lower SES groups.

CONCLUSIONS

SES is inversely associated with ESRD outcomes in individuals with diabetes, and this disparity is reduced in those ≥65 years of age who universally receive prescription drug coverage. Low SES is associated with a higher mortality after dialysis, largely explained by lower kidney transplantation rates in poorer populations.

Initiating Maintenance Dialysis Before Living Kidney Donor Transplantation When a Donor Candidate Evaluation Is Well Underway

BACKGROUND

Preemptive kidney transplants result in better outcomes and patient experiences than transplantation after dialysis onset. It is unknown how often a person initiates maintenance dialysis before living kidney donor transplantation when their donor candidate evaluation is well underway.

METHODS

Using healthcare databases, we retrospectively studied 478 living donor kidney transplants from 2004 to 2014 across 5 transplant centers in Ontario, Canada, where the recipients were not receiving dialysis when their donor's evaluation was well underway. We also explored some factors associated with a higher likelihood of dialysis initiation before transplant.

RESULTS

A total of 167 (35%) of 478 persons with kidney failure initiated dialysis in a median of 9.7 months (25th-75th percentile, 5.4-18.7 months) after their donor candidate began their evaluation and received dialysis for a median of 8.8 months (3.6-16.9 months) before kidney transplantation. The total cohort's dialysis cost was CAD $8.1 million, and 44 (26%) of 167 recipients initiated their dialysis urgently in hospital. The median total donor evaluation time (time from evaluation start to donation) was 10.6 months (6.4-21.6 months) for preemptive transplants and 22.4 months (13.1-38.7 months) for donors whose recipients started dialysis before transplant. Recipients were more likely to start dialysis if their donor was female, nonwhite, lived in a lower-income neighborhood, and if the transplant center received the recipient referral later.

CONCLUSION

One third of persons initiated dialysis before receiving their living kidney donor transplant, despite their donor's evaluation being well underway. Future studies should consider whether some of these events can be prevented by addressing inappropriate delays to improve patient outcomes and reduce healthcare costs.

Association of Nonsteroidal Anti-inflammatory Drug Prescriptions With Kidney Disease Among Active Young and Middle-aged Adults

IMPORTANCE

Concern about the renal effects of nonsteroidand al anti-inflammatory drugs (NSAIDs) among young, healthy adults has been limited, but more attention may be warranted given the prevalent use of these agents.

OBJECTIVE

To test for associations between dispensed NSAIDs and incident acute kidney injury and chronic kidney disease while controlling for other risk factors.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, longitudinal cohort study used deidentified medical and administrative data on 764 228 active-duty US Army soldiers serving between January 1, 2011, and December 31, 2014. Analysis was conducted from August 1 to November 30, 2018. All individuals new to Army service were included in the analysis. Persons already serving in January 2011 were required to have at least 7 months of observable time to eliminate those with kidney disease histories.

EXPOSURES

Mean total defined daily doses of prescribed NSAIDs dispensed per month in the prior 6 months.

MAIN OUTCOMES AND MEASURES

Incident outcomes were defined by diagnoses documented in health records and a military-specific digital system.

RESULTS

Among the 764 228 participants (655 392 [85.8%] men; mean [SD] age, 28.6 [7.9] years; median age, 27.0 years [interquartile range, 22.0-33.0 years]), 502 527 (65.8%) were not dispensed prescription NSAIDs in the prior 6 months, 137 108 (17.9%) were dispensed 1 to 7 mean total defined daily doses per month, and 124 594 (16.3%) received more than 7 defined daily doses per month. There were 2356 acute kidney injury outcomes (0.3% of participants) and 1634 chronic kidney disease outcomes (0.2%) observed. Compared with participants who received no medication, the highest exposure level was associated with significantly higher adjusted hazard ratios (aHRs) for acute kidney injury (aHR, 1.2; 95% CI, 1.1-1.4) and chronic kidney disease (aHR, 1.2; 95% CI, 1.0-1.3), with annual outcome excesses per 100 000 exposed individuals totaling 17.6 cases for acute kidney injury and 30.0 cases for chronic kidney disease.

CONCLUSIONS AND RELEVANCE

Modest but statistically significant associations were noted between the highest observed doses of NSAID exposure and incident kidney problems among active young and middle-aged adults.

Frequency and Associations of Prescription Nonsteroidal Anti-inflammatory Drug Use Among Patients With a Musculoskeletal Disorder and Hypertension, Heart Failure, or Chronic Kidney Disease

IMPORTANCE

International nephrology societies advise against nonsteroidal anti-inflammatory drug (NSAID) use in patients with hypertension, heart failure, or chronic kidney disease (CKD); however, recent studies have not investigated the frequency or associations of use in these patients.

OBJECTIVES

To estimate the frequency of and variation in prescription NSAID use among high-risk patients, to identify characteristics associated with prescription NSAID use, and to investigate whether use is associated with short-term, safety-related outcomes.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, administrative claims databases were linked to create a cohort of primary care visits for a musculoskeletal disorder involving patients 65 years and older with a history of hypertension, heart failure, or CKD between April 1, 2012, and March 31, 2016, in Ontario, Canada.

EXPOSURE

Prescription NSAID use was defined as at least 1 patient-level Ontario Drug Benefit claim for a prescription NSAID dispensing within 7 days after a visit.

MAIN OUTCOMES AND MEASURES

Multiple cardiovascular and renal safety-related outcomes were observed between 8 and 37 days after each visit, including cardiac complications (any emergency department visit or hospitalization for cardiovascular disease), renal complications (any hospitalization for hyperkalemia, acute kidney injury, or dialysis), and death.

RESULTS

The study identified 2 415 291 musculoskeletal-related primary care visits by 814 049 older adults (mean [SD] age, 75.3 [4.0] years; 61.1% female) with hypertension, heart failure, or CKD, of which 224 825 (9.3%) were followed by prescription NSAID use. The median physician-level prescribing rate was 11.0% (interquartile range, 6.7%-16.7%) among 7365 primary care physicians. Within a sample of 35 552 matched patient pairs, each consisting of an exposed and nonexposed patient matched on the logit of their propensity score for prescription NSAID use (exposure), the study found similar rates of cardiac complications (288 [0.8%] vs 279 [0.8%]), renal complications (34 [0.1%] vs 33 [0.1%]), and death (27 [0.1%] vs 30 [0.1%]). For cardiovascular and renal-safety related outcomes, there was no difference between exposed patients (308 [0.9%]) and nonexposed patients (300 [0.8%]) (absolute risk reduction, 0.0003; 95% CI, -0.001 to 0.002; P = .74).

CONCLUSIONS AND RELEVANCE

While prescription NSAID use in primary care was frequent among high-risk patients, with widespread physician-level variation, use was not associated with increased risk of short-term, safety-related outcomes.

Comparing Five Comorbidity Indices to Predict Mortality in Chronic Kidney Disease: A Retrospective Cohort Study

Background:

Several different indices summarize patient comorbidity using health care data. An accurate index can be used to describe the risk profile of patients, and as an adjustment factor in analyses. How well these indices perform in persons with chronic kidney disease (CKD) is not well known.

Objective:

Assess the performance of 5 comorbidity indices at predicting mortality in 3 different patient groups with CKD: incident kidney transplant recipients, maintenance dialysis patients, and individuals with low estimated glomerular filtration rate (eGFR).

Design:

Population-based retrospective cohort study.

Setting:

Ontario, Canada, between 2004 and 2014.

Patients:

Individuals at the time they first received a kidney transplant, received maintenance dialysis, or were confirmed to have an eGFR less than 45 mL/min per 1.73m².

Measurements:

Five comorbidity indices: Charlson comorbidity index, end-stage renal disease-modified Charlson comorbidity index, Johns Hopkins’ Aggregated Diagnosis Groups score, Elixhauser score, and Wright-Khan index. Our primary outcome was 1-year all-cause mortality.

Methods:

Comorbidity indices were estimated using information in the prior 2 years. Each group was randomly divided 100 times into derivation and validation samples. Model discrimination was assessed using median c-statistics from logistic regression models, and calibration was evaluated graphically.

Results:

We identified 4111 kidney transplant recipients, 23 897 individuals receiving maintenance dialysis, and 181 425 individuals with a low eGFR. Within 1 year, 108 (2.6%), 4179 (17.5%), and 17 898 (9.9%) in each group had died, respectively. In the validation sample, model discrimination was inadequate with median c-statistics less than 0.7 for all 5 comorbidity indices for all 3 groups. Calibration was also poor for all models.

Limitations:

The study used administrative health care data so there is the potential for misclassification. Indices were modeled as continuous scores as opposed to indicators for individual conditions to limit overfitting.

Conclusions:

Existing comorbidity indices do not accurately predict 1-year mortality in patients with CKD. Current indices could be modified with additional risk factors to improve their performance in CKD, or a new index could be developed for this population.

Profile of CPAP treated patients in Ontario, Canada, 2006-2013: a population-based cohort study

RATIONALE

Many studies have demonstrated the benefits of treating obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP). However, both recognition of OSA and acceptance of treatment are suboptimal. Current data on CPAP initiation at a population level is lacking.

OBJECTIVES

The objectives were to determine the rate of CPAP initiations in Ontario, Canada (population ∼13,000,000), and to profile these individuals over time.

METHODS

We conducted a population based cohort study between 2006 and 2013. All adults who initiated CPAP for OSA were included. Patient characteristics, comorbidities and health care utilization at the time of CPAP initiation were derived from provincial health administrative data. Changes in patient characteristics over time were assessed.

RESULTS

Over eight years, 216,514 individuals initiated CPAP therapy in comparison to 802,188 individuals who underwent diagnostic polysomnography (PSG) during that time. The rate of new CPAP initiations increased from 18.6/10,000 in 2006 to 28.7/10,000 in 2008 and then plateaued with an annual increase of less than 1/10,000 from 2008 to 2013. More women and middle aged (50+) individuals initiated CPAP as did more low income Ontarians. Comorbidities were common and the frequency of congestive heart failure, chronic kidney disease, and cancer increased during the study period.

CONCLUSIONS

Over an eight year period CPAP initiation appears to have plateaued in spite of increasing PSG testing; however, those receiving treatment with CPAP are increasingly complex and a greater proportion are women.

The association between C-reactive protein levels and the risk for chronic kidney disease hospitalizations in adults of a remote Indigenous Australian community - A prospective cohort study

BACKGROUND

Indigenous Australians are significantly burdened by chronic kidney disease (CKD). Elevated levels of C-reactive protein (CRP) have been associated with diabetes and cardiovascular incidence in previous studies. Elevated CRP has been associated with albuminuria and reduced eGFR in cross-sectional studies. This study investigated the long-term predictive association between CRP measured at a baseline exam and the incidence of a CKD-related hospitalization.

METHODS

Health screening examinations were conducted in individuals of a remote indigenous Australian community between 1992 and 1998. The risk of subsequent CKD hospitalisations, documented through Northern Territory hospital records up to 2010, was estimated with Cox proportional hazard models in people aged over 18 years at the baseline screen and who had albumin-creatinine ratios (ACRs) less than 34g/mol.

RESULTS

546 participants were eligible for our study. Individuals in the highest CRP tertile at baseline had increased levels of traditional cardiovascular risk factors. They also had almost 4 times the risk of a CKD-related hospitalisation compared with participants in the lowest CRP tertile (HR=3.91, 95%CI 1.01-15.20, P=0.049) after adjustment for potential confounding factors. Participants with CRP concentrations greater than 3mg/L had almost 3 times the risk of CKD hospitalisations than those ≤3mg/L (HR=2.84, 95%CI 1.00-8.00, P=0.049). Furthermore, risk of CKD hospitalisations increased 34% per doubling of baseline CRP (HR=1.34, 95%CI 1.04-1.74, P=0.024).

CONCLUSION

In individuals in this remote indigenous community without overt albuminuria at baseline the risk for incident CKD related hospitalisations was predicted by elevated C-reactive protein levels almost a decade earlier. Further research is needed to understand the roles that CRP and systemic inflammation play in CKD risk.

Association Between Newborn Metabolic Profiles and Pediatric Kidney Disease

INTRODUCTION

Metabolomics offers considerable promise in early disease detection. We set out to test the hypothesis that routine newborn metabolic profiles at birth, obtained through screening for inborn errors of metabolism, would be associated with kidney disease and add incremental information to known clinical risk factors.

METHODS

We conducted a population-level cohort study in Ontario, Canada, using metabolic profiles from 1,288,905 newborns from 2006 to 2015. The primary outcome was chronic kidney disease (CKD) or dialysis. Individual metabolites and their ratio combinations were examined by logistic regression after adjustment for established risk factors for kidney disease and incremental risk prediction measured.

RESULTS

CKD occurred in 2086 (0.16%, median time 612 days) and dialysis in 641 (0.05%, median time 99 days) infants and children. Individual metabolites consisted of amino acids, acylcarnitines, markers of fatty acid oxidation, and others. Base models incorporating clinical risk factors only provided c-statistics of 0.61 for CKD and 0.70 for dialysis. The addition of identified metabolites to risk prediciton models resulted in significant incremental improvement in the performance of both models (CKD model: c-statistic 0.66 NRI 0.36 IDI 0.04, dialysis model: c-statistic 0.77 NRI 0.57 IDI 0.09). This was consistent after internal validation using bootstrapping and a sensitivity analysis excluding outcomes within the first 30 days.

CONCLUSION

Routinely collected screening metabolites at birth are associated with CKD and the need for dialytic therapies in infants and children, and add incremental information to traditional clinical risk factors.

The Impact of Diabetes on Breast Cancer Treatments and Outcomes: A Population-Based Study

OBJECTIVE

Women with breast cancer and diabetes face worse outcomes than those with breast cancer without diabetes; however, the contribution of comorbidity to these disparities remains unclear. We evaluated the impact of diabetes on receipt of cancer treatments as well as mortality while accounting for other comorbidities.

RESEARCH DESIGN AND METHODS

Ontario administrative databases were used to compare the rate of receipt of breast cancer treatments between women with and without diabetes. We also performed adjusted cause-specific hazard models to account for comorbidities when evaluating differences in treatments received and mortality outcomes between the two groups.

RESULTS

Women with diabetes and stage III breast cancer were slightly less likely to receive chemotherapy (relative risk [RR] 0.93 [95% CI 0.89-0.97]), although this difference was not significant when we adjusted for comorbidities (adjusted hazard ratio [aHR] 1.03 [95% CI 0.93-1.13]). We saw similar trends for receipt of guideline-adherent radiotherapy (RR 0.97 [0.95-0.99], aHR 0.98 [0.94-1.02]). All-cause mortality was increased in women with diabetes after adjusting for comorbidities (aHR 1.16 [1.06-1.27]), but breast cancer-specific mortality was not increased overall. Women with a longer duration of diabetes and those with preexisting cardiovascular disease had increased all-cause and cancer-specific mortality.

CONCLUSIONS

Although cancer treatments received were similar between women with and without diabetes, breast cancer-specific mortality remains higher among women with diabetes who have longer diabetes duration or preexisting cardiovascular disease. This study uncovers new information about key risk factors for poorer prognosis in women with diabetes and breast cancer.

Gabapentin dose and the 30-day risk of altered mental status in older adults: A retrospective population-based study

Gabapentin is an effective treatment for chronic neuropathic pain but may cause dizziness, drowsiness, and confusion in some older adults. The goal of this study was to assess the association between gabapentin dosing and adverse outcomes by obtaining estimates of the 30-day risk of hospitalization with altered mental status and mortality in older adults (mean age 76 years) in Ontario, Canada initiated on high dose (>600 mg/day; n = 34,159) compared to low dose (≤600 mg/day; n = 76,025) oral gabapentin in routine outpatient care. A population-based, retrospective cohort study assessing new gabapentin use between 2002 to 2014 was conducted. The primary outcome was 30-day hospitalization with an urgent head computed tomography (CT) scan in the absence of evidence of stroke (a proxy for altered mental status). The secondary outcome was 30-day all-cause mortality. The baseline characteristics measured in the two dose groups were similar. Initiation of a high versus low dose of gabapentin was associated with a higher risk of hospitalization with head CT scan (1.27% vs. 1.06%, absolute risk difference 0.21%, adjusted relative risk 1.29 [95% CI 1.14 to 1.46], number needed to treat 477) but not a statistically significant higher risk of mortality (1.25% vs. 1.16%, absolute risk difference of 0.09%, adjusted relative risk of 1.01 [95% CI 0.89 to 1.14]). Overall, the risk of being hospitalized with altered mental status after initiating gabapentin remains low, but may be reduced through the judicious use of gabapentin, use of the lowest dose to control pain, and vigilance for early signs of altered mental status.

Comparative safety of direct oral anticoagulants and warfarin in venous thromboembolism: multicentre, population based, observational study

Objective To determine the safety of direct oral anticoagulant (DOAC) use compared with warfarin use for the treatment of venous thromboembolism.Design Retrospective matched cohort study conducted between 1 January 2009 and 31 March 2016.Setting Community based, using healthcare data from six jurisdictions in Canada and the United States.Participants 59 525 adults (12 489 DOAC users; 47 036 warfarin users) with a new diagnosis of venous thromboembolism and a prescription for a DOAC or warfarin within 30 days of diagnosis.Main outcome measures Outcomes included hospital admission or emergency department visit for major bleeding and all cause mortality within 90 days after starting treatment. Propensity score matching and shared frailty models were used to estimate adjusted hazard ratios of the outcomes comparing DOACs with warfarin. Analyses were conducted independently at each site, with meta-analytical methods used to estimate pooled hazard ratios across sites.Results Of the 59 525 participants, 1967 (3.3%) had a major bleed and 1029 (1.7%) died over a mean follow-up of 85.2 days. The risk of major bleeding was similar for DOAC compared with warfarin use (pooled hazard ratio 0.92, 95% confidence interval 0.82 to 1.03), with the overall direction of the association favouring DOAC use. No difference was found in the risk of death (pooled hazard ratio 0.99, 0.84 to 1.16) for DOACs compared with warfarin use. There was no evidence of heterogeneity across centres, between patients with and without chronic kidney disease, across age groups, or between male and female patients.Conclusions In this analysis of adults with incident venous thromboembolism, treatment with DOACs, compared with warfarin, was not associated with an increased risk of major bleeding or all cause mortality in the first 90 days of treatment.Trial registration Clinical trials NCT02833987.

Gabapentin, opioids, and the risk of opioid-related death: A population-based nested case-control study

BACKGROUND

Prescription opioid use is highly associated with risk of opioid-related death, with 1 of every 550 chronic opioid users dying within approximately 2.5 years of their first opioid prescription. Although gabapentin is widely perceived as safe, drug-induced respiratory depression has been described when gabapentin is used alone or in combination with other medications. Because gabapentin and opioids are both commonly prescribed for pain, the likelihood of co-prescription is high. However, no published studies have examined whether concomitant gabapentin therapy is associated with an increased risk of accidental opioid-related death in patients receiving opioids. The objective of this study was to investigate whether co-prescription of opioids and gabapentin is associated with an increased risk of accidental opioid-related mortality.

METHODS AND FINDINGS

We conducted a population-based nested case-control study among opioid users who were residents of Ontario, Canada, between August 1, 1997, and December 31, 2013, using administrative databases. Cases, defined as opioid users who died of an opioid-related cause, were matched with up to 4 controls who also used opioids on age, sex, year of index date, history of chronic kidney disease, and a disease risk index. After matching, we included 1,256 cases and 4,619 controls. The primary exposure was concomitant gabapentin use in the 120 days preceding the index date. A secondary analysis characterized gabapentin dose as low (<900 mg daily), moderate (900 to 1,799 mg daily), or high (≥1,800 mg daily). A sensitivity analysis examined the effect of concomitant nonsteroidal anti-inflammatory drug (NSAID) use in the preceding 120 days. Overall, 12.3% of cases (155 of 1,256) and 6.8% of controls (313 of 4,619) were prescribed gabapentin in the prior 120 days. After multivariable adjustment, co-prescription of opioids and gabapentin was associated with a significantly increased odds of opioid-related death (odds ratio [OR] 1.99, 95% CI 1.61 to 2.47, p < 0.001; adjusted OR [aOR] 1.49, 95% CI 1.18 to 1.88, p < 0.001) compared to opioid prescription alone. In the dose-response analysis, moderate-dose (OR 2.05, 95% CI 1.46 to 2.87, p < 0.001; aOR 1.56, 95% CI 1.06 to 2.28, p = 0.024) and high-dose (OR 2.20, 95% CI 1.58 to 3.08, p < 0.001; aOR 1.58, 95% CI 1.09 to 2.27, p = 0.015) gabapentin use was associated with a nearly 60% increase in the odds of opioid-related death relative to no concomitant gabapentin use. As expected, we found no significant association between co-prescription of opioids and NSAIDs and opioid-related death (OR 1.11, 95% CI 0.98 to 1.27, p = 0.113; aOR 1.14, 95% CI 0.98 to 1.32, p = 0.083). In an exploratory analysis of patients at risk of combined opioid and gabapentin use, we found that 46.0% (45,173 of 98,288) of gabapentin users in calendar year 2013 received at least 1 concomitant prescription for an opioid. This study was limited to individuals eligible for public drug coverage in Ontario, we were only able to identify prescriptions reimbursed by the government and dispensed from retail pharmacies, and information on indication for gabapentin use was not available. Furthermore, as with all observational studies, confounding due to unmeasured variables is a potential source of bias.

CONCLUSIONS

In this study we found that among patients receiving prescription opioids, concomitant treatment with gabapentin was associated with a substantial increase in the risk of opioid-related death. Clinicians should consider carefully whether to continue prescribing this combination of products and, when the combination is deemed necessary, should closely monitor their patients and adjust opioid dose accordingly. Future research should investigate whether a similar interaction exists between pregabalin and opioids.

A scheme based on ICD-10 diagnoses and drug prescriptions to stage chronic kidney disease severity in healthcare administrative records

Background

Information about renal function is important for drug safety studies using administrative health databases. However, serum creatinine values are seldom available in these registries. Our aim was to develop and test a simple scheme for stratification of renal function without access to laboratory test results.

Methods

Our scheme uses registry data about diagnoses, contacts, dialysis and drug use. We validated the scheme in the Stockholm CREAtinine Measurements (SCREAM) project using information on approximately 1.1 million individuals residing in the Stockholm County who underwent calibrated creatinine testing during 2006–11, linked with data about health care contacts and filled drug prescriptions. Estimated glomerular filtration rate (eGFR) was calculated with the CKD-EPI formula and used as the gold standard for validation of the scheme.

Results

When the scheme classified patients as having eGFR <30 mL/min/1.73 m², it was correct in 93.5% of cases. The specificity of the scheme was close to 100% in all age groups. The sensitivity was poor, ranging from 68.2% in the youngest age quartile, down to 10.7% in the oldest age quartile. Age-related decline in renal function makes a large proportion of elderly patients fall into the chronic kidney disease (CKD) range without receiving CKD diagnoses, as this often is seen as part of normal ageing.

Conclusions

In the absence of renal function tests, our scheme may be of value for identifying patients with moderate and severe CKD on the basis of diagnostic and prescription data for use in studies of large healthcare databases.

Estimating One-Year Risk of Incident Chronic Kidney Disease: Retrospective Development and Validation Study Using Electronic Medical Record Data From the State of Maine

Background

Chronic kidney disease (CKD) is a major public health concern in the United States with high prevalence, growing incidence, and serious adverse outcomes.

Objective

We aimed to develop and validate a model to identify patients at risk of receiving a new diagnosis of CKD (incident CKD) during the next 1 year in a general population.

Methods

The study population consisted of patients who had visited any care facility in the Maine Health Information Exchange network any time between January 1, 2013, and December 31, 2015, and had no history of CKD diagnosis. Two retrospective cohorts of electronic medical records (EMRs) were constructed for model derivation (N=1,310,363) and validation (N=1,430,772). The model was derived using a gradient tree-based boost algorithm to assign a score to each individual that measured the probability of receiving a new diagnosis of CKD from January 1, 2014, to December 31, 2014, based on the preceding 1-year clinical profile. A feature selection process was conducted to reduce the dimension of the data from 14,680 EMR features to 146 as predictors in the final model. Relative risk was calculated by the model to gauge the risk ratio of the individual to population mean of receiving a CKD diagnosis in next 1 year. The model was tested on the validation cohort to predict risk of CKD diagnosis in the period from January 1, 2015, to December 31, 2015, using the preceding 1-year clinical profile.

Results

The final model had a c-statistic of 0.871 in the validation cohort. It stratified patients into low-risk (score 0-0.005), intermediate-risk (score 0.005-0.05), and high-risk (score ≥ 0.05) levels. The incidence of CKD in the high-risk patient group was 7.94%, 13.7 times higher than the incidence in the overall cohort (0.58%). Survival analysis showed that patients in the 3 risk categories had significantly different CKD outcomes as a function of time (P<.001), indicating an effective classification of patients by the model.

Conclusions

We developed and validated a model that is able to identify patients at high risk of having CKD in the next 1 year by statistically learning from the EMR-based clinical history in the preceding 1 year. Identification of these patients indicates care opportunities such as monitoring and adopting intervention plans that may benefit the quality of care and outcomes in the long term.

A rule-based electronic phenotyping algorithm for detecting clinically relevant cardiovascular disease cases

Background

The implementation of electronic medical records (EMR) is becoming increasingly common. Error and data loss reduction, patient-care efficiency increase, decision-making assistance and facilitation of event surveillance, are some of the many processes that EMRs help improve. In addition, they show a lot of promise in terms of data collection to facilitate observational epidemiological studies and their use for this purpose has increased significantly over the recent years. Even though the quantity and availability of the data are clearly improved thanks to EMRs, still, the problem of the quality of the data remains. This is especially important when attempting to determine if an event has actually occurred or not. We sought to assess the sensitivity, specificity, and agreement level of a codes-based algorithm for the detection of clinically relevant cardiovascular (CaVD) and cerebrovascular (CeVD) disease cases, using data from EMRs.

Methods

Three family physicians from the research group selected clinically relevant CaVD and CeVD terms from the international classification of primary care, Second Edition (ICPC-2), the ICD 10 version 2015 and SNOMED-CT 2015 Edition. These terms included both signs, symptoms, diagnoses and procedures associated with CaVD and CeVD. Terms not related to symptoms, signs, diagnoses or procedures of CaVD or CeVD and also those describing incidental findings without clinical relevance were excluded. The algorithm yielded a positive result if the patient had at least one of the selected terms in their medical records, as long as it was not recorded as an error. Else, if no terms were found, the patient was classified as negative. This algorithm was applied to a randomly selected sample of the active patients within the hospital’s HMO by 1/1/2005 that were 40–79 years old, had at least one year of seniority in the HMO and at least one clinical encounter. Thus, patients were classified into four groups: (1) Negative patients (2) Patients with CaVD but without CeVD; (3) Patients with CeVD but without disease CaVD; (4) Patients with both diseases. To facilitate the validation process, a stratified sample was taken so that each of the groups represented approximately 25% of the sample. Manual chart review was used as the gold standard for assessing the algorithm’s performance. One-third of the patients were assigned randomly to each reviewer (Cohen’s kappa 0.91). Both coded and un-coded (free text) sections of the EMR were reviewed. This was done from the first present clinical note in the patients chart to the last one registered prior to 1/1/2005.

Results

The performance of the algorithm was compared against manual chart review. It yielded high sensitivity (0.99, 95% CI 0.938–0.9971) and acceptable specificity (0.86, 95% CI 0.818–0.895) for detecting cases of CaVD and CeVD combined. A qualitative analysis of the false positives and false negatives was performed.

Conclusions

We developed a simple algorithm, using only standardized and non-standardized coded terms within an EMR that can properly detect clinically relevant events and symptoms of CaVD and CeVD. We believe that combining it with an analysis of the free text using an NLP approach would yield even better results.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-017-2600-2) contains supplementary material, which is available to authorized users.

Kidney Disease Among Registered Métis Citizens of Ontario: A Population-Based Cohort Study

Background:

Indigenous peoples in Canada have higher rates of kidney disease than non-Indigenous Canadians. However, little is known about the risk of kidney disease specifically in the Métis population in Canada.

Objective:

To compare the prevalence of chronic kidney disease and incidence of acute kidney injury and end-stage kidney disease among registered Métis citizens in Ontario and a matched sample from the general Ontario population.

Design:

Population-based, retrospective cohort study using data from the Métis Nation of Ontario’s Citizenship Registry and administrative databases.

Setting:

Ontario, Canada; 2003-2013.

Patients:

Ontario residents ≥18 years.

Measurements:

Prevalence of chronic kidney disease and incidence of acute kidney injury and end-stage kidney disease. Secondary outcomes among patients hospitalized with acute kidney injury included non-recovery of kidney function and mortality within 1 year of discharge.

Methods:

Database codes and laboratory values were used to determine study outcomes. Métis citizens were matched (1:4) to Ontario residents on age, sex, and area of residence. The analysis included 12 229 registered Métis citizens and 48 916 adults from the general population.

Results:

We found the prevalence of chronic kidney disease was slightly higher among Métis citizens compared with the general population (3.1% vs 2.6%, P = 0.002). The incidence of acute kidney injury was 1.2 per 1000 person-years in both Métis citizens and the general population (P = 0.54). Of those hospitalized with acute kidney injury, outcomes were similar among Métis citizens and the general population except 1-year mortality, which was higher for Métis citizens (24.5% vs 15.3%, P = 0.03). The incidence of end-stage kidney disease did not differ between groups (<3.0 per 10 000 person-years, P = 0.73).

Limitations:

The Métis Nation of Ontario Citizenship Registry only captures about 20% of Métis people in Ontario. Administrative health care codes used to identify kidney disease are highly specific but have low sensitivity.

Conclusions:

Rates of kidney disease were similar or slightly higher for Métis citizens in Ontario compared with the matched general population.

Performance Characteristics of Kidney Injury Molecule-1 In Relation to Creatinine, Urea, and Microalbuminuria in the Diagnosis of Kidney Disease

Context:

The diagnosis and evaluation of impaired renal function remains a challenge owing to lack of reliable biomarker for assessment of kidney function. The existing panel of biomarkers currently displays several limitations, and recently kidney injury molecule-1 (KIM-1) has been suggested as a sensitive biomarker of renal function and proposed to enter clinical practice.

Aims:

This study was conducted to determine the diagnostic value of serum creatinine, urea, and microalbuminuria (MAU) in relation to the novel biomarker, KIM-1.

Materials and Methods:

Serum creatinine, urea, MAU, and KIM-1 were measured in forty individuals with and forty without kidney disease. Data were analyzed using multivariate methods of assessing diagnostic efficiency, test agreement, condition effects, and variability.

Results:

The area under the receiver-operator characteristic curve revealed a diagnostic advantage of creatinine (0.924 ± 0.0066) and urea (0.925 ± 0.0068) over MAU (0.880 ± 0.078) and KIM-1 (0.35 ± 0.124). Overall diagnostic efficiency was higher for creatinine and urea (89.5% and 90.9%, respectively), followed by MAU (85.7%) and then KIM-1 (56.3%). Logistic regression analysis showed that creatinine and urea (R² = 0.75 and R² = 0.72, respectively, P < 0.001 for both) were better predictors of kidney disease than MAU (R² = 0.64, P < 0.001) and KIM-1 (R² = 0.046, P = 0.116). Further analysis of agreement showed that urea had an excellent agreement with creatinine (kappa r = 0.835, P < 0.001), with KIM-1 (kappa r = –0.198, P = 0.087) showing a poor agreement with creatinine.

Conclusion:

Our results indicate that elevated serum creatinine and urea above specific cutoff points reliably identifies patients with acute kidney injury or chronic kidney disease. However, more researches are warranted to further validate the diagnostic efficiency and application of MAU and for KIM-1 before its implementation in clinical practice.

Warfarin Initiation, Atrial Fibrillation, and Kidney Function: Comparative Effectiveness and Safety of Warfarin in Older Adults With Newly Diagnosed Atrial Fibrillation

BACKGROUND

The effectiveness and safety of warfarin use among patients with atrial fibrillation (AF) and reduced kidney function are uncertain.

STUDY DESIGN

Community-based retrospective cohort study (May 1, 2003, to March 31, 2012) using province-wide laboratory and administrative data in Alberta, Canada.

SETTING & PARTICIPANTS

14,892 adults 66 years or older with new AF and a measurement of kidney function. Long-term dialysis patients or kidney transplant recipients were excluded.

PREDICTOR

Propensity scores were used to construct a matched-pairs cohort of patients with AF who did and did not have a warfarin prescription within a 60-day period surrounding their AF diagnosis.

OUTCOMES

Within 1 year of initiating warfarin therapy (or the matched date for nonusers): (1) the composite of all-cause death, ischemic stroke, or transient ischemic attack (also assessed as separate end points) and (2) first hospitalization or emergency department visit for a major bleeding episode defined as an intracranial, upper or lower gastrointestinal, or other bleeding.

MEASUREMENTS

Baseline glomerular filtration rate (GFR) was estimated using the CKD-EPI creatinine equation. Patients were matched within estimated GFR (eGFR) categories: ≥90, 60 to 89, 45 to 59, 30 to 44, and <30mL/min/1.73m². Information for baseline characteristics (sociodemographics, comorbid conditions, and prescription drug use) was obtained.

RESULTS

Across eGFR categories, warfarin therapy initiation was associated with lower risk for the composite outcome compared to nonuse (adjusted HRs [95% CI] for eGFR categories ≥ 90, 60-89, 45-59, 30-44, and <30mL/min/1.73m²: 0.59 [0.35-1.01], 0.61 [0.54-0.70], 0.55 [0.47-0.65], 0.54 [0.44-0.67], and 0.64 [0.47-0.87] mL/min/1.73m², respectively). Compared to nonuse, warfarin therapy was not associated with higher risk for major bleeding except for those with eGFRs of 60 to 89mL/min/1.73m² (HR, 1.36; 95% CI, 1.13-1.64).

LIMITATIONS

Selection bias.

CONCLUSIONS

Among older adults with AF, warfarin therapy initiation was associated with a significantly lower 1-year risk for the composite outcome across all strata of kidney function. The risk for major bleeding associated with warfarin use was increased only among those with eGFRs of 60 to 89mL/min/1.73m².

Second-Generation Antidepressants and Hyponatremia Risk: A Population-Based Cohort Study of Older Adults

BACKGROUND

Hyponatremia may occur after initiation of a second-generation antidepressant drug. However, the magnitude of this risk among older adults in routine care is not well characterized.

STUDY DESIGN

Retrospective, population-based, matched-cohort study.

SETTING & PARTICIPANTS

In Ontario, Canada, 2003 to 2012, we compared older adults with a mood or anxiety disorder who were dispensed 1 of 9 second-generation antidepressant drugs with matched adults with comparable indicators of baseline health who were not dispensed an antidepressant drug (n=138,246 per group). A similar comparison was made in a subpopulation with available laboratory data (n=4,186 per group).

PREDICTOR

Second-generation antidepressant prescription versus no antidepressant prescription.

OUTCOMES

The primary outcome was hospitalization with hyponatremia. A secondary outcome was hospitalization with both hyponatremia and delirium.

MEASUREMENTS

We assessed hospitalization with hyponatremia using a diagnosis code and, in the subpopulation, serum sodium values. We assessed hospitalization with hyponatremia and delirium using a combination of diagnosis codes.

RESULTS

Second-generation antidepressant use versus nonuse was associated with higher 30-day risk for hospitalization with hyponatremia (450/138,246 [0.33%] vs 84/138,246 [0.06%]; relative risk [RR], 5.46 [95% CI, 4.32-6.91]). This association was consistent in the subpopulation with serum sodium values (73/4,186 [1.74%] vs 18/4,186 [0.43%]; RR, 4.23 [95% CI, 2.50-7.19]; absolute risk increase, 1.31% [95% CI, 0.87%-1.75%]). Second-generation antidepressant use versus nonuse was also associated with higher 30-day risk for hospitalization with both hyponatremia and delirium (28/138,246 [0.02%] vs 7/138,246 [0.005%]; RR, 4.00 [95% CI, 1.75-9.16]).

LIMITATIONS

Measures of serum sodium could be ascertained in only a subpopulation.

CONCLUSIONS

Use of a second-generation antidepressant in routine care by older adults is associated with an approximate 5-fold increase in 30-day risk for hospitalization with hyponatremia compared to nonuse. However, the absolute increase in 30-day incidence is low.

Time to follow-up of an abnormal mammogram in women with diabetes: a population-based study

Women with diabetes have a higher breast cancer incidence and mortality. They are also significantly less likely to undergo screening mammography and present with more advanced stage than women without diabetes. The purpose of this study was to examine if women with diabetes are more likely to have delays in follow-up of abnormal mammograms, compared to women without diabetes. Using population-based health databases, this retrospective cohort study examined women between the ages of 50 and 74, with and without diabetes, living in the province of Ontario, Canada, who underwent screening through a centralized program and who had an abnormal mammogram between 2003 and 2012. We compared rates of follow-up of a diagnostic test within 180 days, as well as likelihood of mastectomy or excision procedure and a diagnosis of breast cancer. Following an abnormal screening mammogram, 97.5% of women with diabetes had a diagnostic procedure within 180 days compared to 97.9% of women without diabetes. After adjustment for other factors, women with diabetes were only 3% less likely to have follow-up testing after an abnormal mammogram than women without diabetes (hazard ratio [HR] 0.97, 95% CI: 0.96-0.99, P < 0.001). The majority of Ontario women who underwent screening mammography through a centralized screening program had timely follow-up of an abnormal mammogram, with no meaningful delays in those who had diabetes. The results of this study suggest that diagnostic delays after screening do not significantly contribute to higher breast cancer mortality in women with diabetes.

Risk of Ventricular Arrhythmia with Citalopram and Escitalopram: A Population-Based Study

Background

The risk of ventricular arrhythmia with citalopram and escitalopram is controversial. In this study we investigated the association between these two drugs and the risk of ventricular arrhythmia.

Methods

We conducted a population-based retrospective cohort study of older adults (mean age 76 years) from 2002 to 2012 in Ontario, Canada, newly prescribed citalopram (n = 137 701) or escitalopram (n = 38 436), compared to those prescribed referent antidepressants sertraline or paroxetine (n = 96 620). After inverse probability of treatment weighting using a propensity score, the baseline characteristics of the comparison groups were similar. The primary outcome was a hospital encounter with ventricular arrhythmia within 90 days of a new prescription, assessed using hospital diagnostic codes. The secondary outcome was all-cause mortality within 90 days.

Results

Citalopram was associated with a higher risk of a hospital encounter with ventricular arrhythmia compared with referent antidepressants (0.06% vs. 0.04%, relative risk [RR] 1.53, 95% confidence intervals [CI]1.03 to 2.29), and a higher risk of mortality (3.49% vs. 3.12%, RR 1.12, 95% CI 1.06 to 1.18). Escitalopram was not associated with a higher risk of ventricular arrhythmia compared with the referent antidepressants (0.03% vs. 0.04%, RR 0.84, 95% CI 0.42 to 1.68), but was associated with a higher risk of mortality (2.86% vs. 2.63%, RR 1.09, 95% CI 1.01 to 1.18).

Conclusion

Among older adults, initiation of citalopram compared to two referent antidepressants was associated with a small but statistically significant increase in the 90-day risk of a hospital encounter for ventricular arrhythmia.

Global Prevalence of Chronic Kidney Disease - A Systematic Review and Meta-Analysis

Chronic kidney disease (CKD) is a global health burden with a high economic cost to health systems and is an independent risk factor for cardiovascular disease (CVD). All stages of CKD are associated with increased risks of cardiovascular morbidity, premature mortality, and/or decreased quality of life. CKD is usually asymptomatic until later stages and accurate prevalence data are lacking. Thus we sought to determine the prevalence of CKD globally, by stage, geographical location, gender and age. A systematic review and meta-analysis of observational studies estimating CKD prevalence in general populations was conducted through literature searches in 8 databases. We assessed pooled data using a random effects model. Of 5,842 potential articles, 100 studies of diverse quality were included, comprising 6,908,440 patients. Global mean(95%CI) CKD prevalence of 5 stages 13·4%(11·7-15·1%), and stages 3-5 was 10·6%(9·2-12·2%). Weighting by study quality did not affect prevalence estimates. CKD prevalence by stage was Stage-1 (eGFR>90+ACR>30): 3·5% (2·8-4·2%); Stage-2 (eGFR 60-89+ACR>30): 3·9% (2·7-5·3%); Stage-3 (eGFR 30-59): 7·6% (6·4-8·9%); Stage-4 = (eGFR 29-15): 0·4% (0·3-0·5%); and Stage-5 (eGFR<15): 0·1% (0·1-0·1%). CKD has a high global prevalence with a consistent estimated global CKD prevalence of between 11 to 13% with the majority stage 3. Future research should evaluate intervention strategies deliverable at scale to delay the progression of CKD and improve CVD outcomes.

Using physician billing claims from the Ontario Health Insurance Plan to determine individual influenza vaccination status: an updated validation study

BACKGROUND

Owing to the absence of a vaccination registry in Ontario, administrative data are currently the best available source to determine population-based individual-level influenza vaccination status. Our objective was to validate physician billing claims for influenza vaccination in the Ontario Health Insurance Plan database against the Canadian Community Health Survey.

METHODS

We used self-reported seasonal influenza vaccination status of Ontario residents surveyed between 2007 and 2009 as the reference standard. The survey responses were linked to physician claims database records to validate billing codes for influenza vaccination. We calculated sensitivity, specificity, positive predictive value and negative predictive value with 95% confidence intervals (CIs). We stratified the data by several covariates and comorbidities to determine stratum-specific performance characteristics. We used these estimates to adjust an estimate of influenza vaccine effectiveness for the 2010/11 influenza season.

RESULTS

For the 47 301 patients included in the analysis, the sensitivity for the billing codes was 49.8% (95% CI 49.0%-50.5%), specificity was 95.7% (95% CI 95.5%-96.0%), positive predictive value was 88.4% (95% CI 87.8%-89.0%) and negative predictive value was 74.5% (95% CI 74.0%-74.9%). Performance measures were optimized in patients aged 65 years and older, particularly those with comorbidities.

INTERPRETATION

Although administrative data have limitations for determining influenza vaccination status, owing to the high positive predictive value, they are well suited for self-controlled study designs that are often used to assess vaccine safety. For studies of coverage and effectiveness, restricting the cohort to patients aged 65 years and older will minimize misclassification bias. Performance characteristics from this study can be used to mitigate misclassification bias.

Fracture Incidence in Adult Kidney Transplant Recipients

BACKGROUND

It remains uncertain whether kidney transplant recipients are a high-risk group for fracture.

METHODS

We conducted a cohort study using Ontario, Canada health care databases to estimate the 3-, 5- and 10-year cumulative incidence of nonvertebral fracture (proximal humerus, forearm, hip) in adult kidney transplant recipients between 1994 and 2009, stratifying by sex and age (<50 versus ≥50 years) at transplant. We also assessed the 3-year cumulative incidence of all fracture locations (excluding skull, toes, and fingers) and falls, 10-year cumulative incidence of hip fracture alone, and nonvertebral fracture incidence in recipients compared to nontransplant reference groups matched on age, sex, and cohort entry year. We studied 4821 recipients (median age, 50 years).

RESULTS

Among the age and sex strata, female recipients aged 50 years or older had the highest 3-year cumulative incidence of nonvertebral fracture (3.1%; 95% confidence interval [95% CI], 2.1-4.4%). Recipients had a higher 3-year cumulative incidence of nonvertebral fracture (1.6%; 95% CI, 1.3-2.0%) compared to the general population with no previous nonvertebral fracture (0.5%; 95% CI, 0.4-0.6%; P < 0.0001) and nondialysis chronic kidney disease (1.1%; 95% CI, 0.9-1.2%; P = 0.03), but a lower fracture incidence than the general population with a previous nonvertebral fracture (2.3%; 95% CI, 1.9-2.8%; P = 0.007). The 10-year cumulative incidence of hip fracture in all recipients was 1.7% (≥3% defined as high risk in clinical guidelines).

CONCLUSIONS

Kidney transplant recipients may have a lower fracture risk than previously suggested in the literature. Results inform our understanding of fracture incidence after kidney transplantation and how it compares to nontransplant populations.

Atypical antipsychotic medications and hyponatremia in older adults: a population-based cohort study

BACKGROUND

A number of case reports have suggested a possible association between atypical antipsychotic medications and hyponatremia. Currently, there are no reliable estimates of hyponatremia risk from atypical antipsychotic drugs.

OBJECTIVE

The objective of this study was to examine the 30-day risk of hospitalization with hyponatremia in older adults dispensed an atypical antipsychotic drug relative to no antipsychotic use.

DESIGN

The design of this study was a retrospective, population-based cohort study.

SETTING

The setting of this study was in Ontario, Canada, from 2003 to 2012.

PATIENTS

Adults 65 years or older with an identified psychiatric condition who were newly dispensed risperidone, olanzapine, or quetiapine in the community setting compared to adults with similar indicators of baseline health who were not dispensed such a prescription.

MEASUREMENTS

The primary outcome was the 30-day risk of hospitalization with hyponatremia. The tracer outcome (an outcome that is not expected to be influenced by the study drugs) was the 30-day risk of hospitalization with bowel obstruction. These outcomes were assessed using hospital diagnosis codes.

METHODS

Using health administrative data, we applied a propensity score technique to match antipsychotic users 1:1 to non-users of antipsychotic drugs (58,008 patients in each group). We used conditional logistic regression to compare outcomes among the matched users and non-users.

RESULTS

A total of 104 baseline characteristics were well-balanced between the two matched groups. Atypical antipsychotic use compared to non-use was associated with an increased risk of hospitalization with hyponatremia within 30 days (86/58,008 (0.15 %) versus 53/58,008 (0.09 %); relative risk 1.62 (95 % confidence interval (CI) 1.15 to 2.29); absolute risk increase 0.06 % (95 % CI 0.02 to 0.10)). The limited number of events precluded some additional analyses to confirm if the association was robust. Atypical antipsychotic use compared to non-use was not associated with hospitalization with bowel obstruction within 30 days (55/58,008 (0.09 %) versus 44/58,008 (0.08 %); relative risk 1.25 (95 % CI 0.84 to 1.86)).

LIMITATIONS

We could only study older adults within our data sources.

CONCLUSIONS

In this study, the use of an atypical antipsychotic was associated with a modest but statistically significant increase in the 30-day risk of a hospitalization with hyponatremia. The association was less pronounced than that described with other psychotropic drugs.

Impact of renal dysfunction on in-hospital mortality of patients with severe chronic obstructive pulmonary disease: a single-center Italian study

BACKGROUND

We conducted a study, based on discharge hospital sheets [International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM)], in order to evaluate the relationship between chronic kidney disease (CKD), acute kidney injury (AKI), multi-morbidity, and in-hospital mortality (IHM).

METHODS

This study included all hospital admissions for chronic obstructive pulmonary disease (COPD) exacerbations between January 1, 2000, and December 31, 2013, recorded in the database of the University Hospital St. Anna of Ferrara. Age, sex, and diagnosis of CKD and AKI were collected, and Charlson comorbidity index (CCI) was calculated by ICD-9-CM codes. IHM was our main outcome.

RESULTS

We analyzed 7073 subjects with COPD exacerbation; they were more frequently male (56.9 vs 43.1 %), and mean age was 76.7 ± 9.8 years. Diagnosis of CKD was present in 771 patients (10.9 %), while AKI was diagnosed in 354 cases (5 %). A total of 554 patients (7.8 %) died during hospitalization, and LOS was 10.3 ± 11.2 days (median 8 days); the CCI corrected for CKD was 2.30 ± 1.65. Univariate analysis showed that IHM group had higher age (81.2 ± 7.9 vs 76.3 ± 9.9 years, p < 0.001), CCI (2.61 ± 2.21 vs 2.28 ± 1.62, p = 0.001), and LOS (11.1 ± 15.1 vs 10.3 ± 10.8 days, p = 0.001) and developed AKI more frequently (16.6 vs 4 %, p < 0.001) than survivors. Multivariate logistic regression analysis showed an independent association of IHM with age (OR 1.063; 95 % CI 1.050-1.075, p < 0.001), male sex (OR 1.229; 95 % CI 1.016-1.486, p = 0.033), logCCI (OR 2.051; 95 % CI 1.419-2.964, p < 0.001), and AKI (OR 3.849; 95 % CI 2.874-5.155, p < 0.001).

CONCLUSIONS

Acute kidney injury (AKI) represents a very important predictive factor of IHM in male older adult with multi-morbidity admitted because of COPD exacerbations.

The influence of chronic kidney disease and age on revascularization rates and outcomes in acute myocardial infarction - a cohort study

BACKGROUND

There is a paucity of data on the complex interaction between chronic kidney disease, age and its impact on management and outcomes in acute myocardial infarction.

METHODS

A state based claims dataset that collects data on all hospitalizations (representing 32.3% of the Australian population) was used to identify all patients admitted with a principal diagnosis of acute myocardial infarction (ICD10 codes: I21.0-I21.4) over a four-year period. Patients were linked to the state death registry and followed until death or end of follow-up (31 December 2009). Chronic kidney disease was defined as the presence of any of 65 ICD10 diagnostic codes for chronic kidney disease. The primary outcomes were receipt of revascularization, length of hospital stay and mortality adjusted for age, comorbidities and prior revascularization at presentation.

RESULTS

Of the 40,472 patients with acute myocardial infarction, chronic kidney disease was present in 4814 patients (11.9%). Median follow-up was 2.8 years (range 0-5.5 years). In the multivariable model, there was a marked interaction between chronic kidney disease and age ( p<0.001). Chronic kidney disease was a powerful marker of lower revascularization rates (median age group of 70-79 years: odds ratio 0.68; 95% confidence interval 0.59-0.78; p<0.001), especially in those over the age of 50 years. The impact of chronic kidney disease on length of stay (median age group of 70-79 years vs. referent age group 18-39 years: incidence rate ratio 1.41; 95% confidence interval 1.32-1.51; p<0.001) and long-term mortality (median age group of 70-79 years: hazard ratio 2.19; 95% confidence interval 2.01-2.39; p<0.001) was mitigated with increasing age.

CONCLUSION

Chronic kidney disease is an important deterrent for the receipt of revascularization in older patients, but age is the primary determinant of length of stay and mortality.