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

Background

Large, population-based administrative healthcare databases can be used to identify patients with chronic kidney disease (CKD) when serum creatinine laboratory results are unavailable. We examined the validity of algorithms that used combined hospital encounter and physician claims database codes for the detection of CKD in Ontario, Canada.

Methods

We accrued 123,499 patients over the age of 65 from 2007 to 2010. All patients had a baseline serum creatinine value to estimate glomerular filtration rate (eGFR). We developed an algorithm of physician claims and hospital encounter codes to search administrative databases for the presence of CKD. We determined the sensitivity, specificity, positive and negative predictive values of this algorithm to detect our primary threshold of CKD, an eGFR <45 mL/min per 1.73 m² (15.4% of patients). We also assessed serum creatinine and eGFR values in patients with and without CKD codes (algorithm positive and negative, respectively).

Results

Our algorithm required evidence of at least one of eleven CKD codes and 7.7% of patients were algorithm positive. The sensitivity was 32.7% [95% confidence interval: (95% CI): 32.0 to 33.3%]. Sensitivity was lower in women compared to men (25.7 vs. 43.7%; p <0.001) and in the oldest age category (over 80 vs. 66 to 80; 28.4 vs. 37.6 %; p < 0.001). All specificities were over 94%. The positive and negative predictive values were 65.4% (95% CI: 64.4 to 66.3%) and 88.8% (95% CI: 88.6 to 89.0%), respectively. In algorithm positive patients, the median [interquartile range (IQR)] baseline serum creatinine value was 135 μmol/L (106 to 179 μmol/L) compared to 82 μmol/L (69 to 98 μmol/L) for algorithm negative patients. Corresponding eGFR values were 38 mL/min per 1.73 m² (26 to 51 mL/min per 1.73 m²) vs. 69 mL/min per 1.73 m² (56 to 82 mL/min per 1.73 m²), respectively.

Conclusions

Patients with CKD as identified by our database algorithm had distinctly higher baseline serum creatinine values and lower eGFR values than those without such codes. However, because of limited sensitivity, the prevalence of CKD was underestimated.

Association Between Handover of Anesthesia Care and Adverse Postoperative Outcomes Among Patients Undergoing Major Surgery

IMPORTANCE

Handing over the care of a patient from one anesthesiologist to another occurs during some surgeries and might increase the risk of adverse outcomes.

OBJECTIVE

To assess whether complete handover of intraoperative anesthesia care is associated with higher likelihood of mortality or major complications compared with no handover of care.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective population-based cohort study (April 1, 2009-March 31, 2015 set in the Canadian province of Ontario) of adult patients aged 18 years and older undergoing major surgeries expected to last at least 2 hours and requiring a hospital stay of at least 1 night.

EXPOSURE

Complete intraoperative handover of anesthesia care from one physician anesthesiologist to another compared with no handover of anesthesia care.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of all-cause death, hospital readmission, or major postoperative complications, all within 30 postoperative days. Secondary outcomes were the individual components of the primary outcome. Inverse probability of exposure weighting based on the propensity score was used to estimate adjusted exposure effects.

RESULTS

Of the 313 066 patients in the cohort, 56% were women; the mean (SD) age was 60 (16) years; 49% of surgeries were performed in academic centers; 72% of surgeries were elective; and the median duration of surgery was 182 minutes (interquartile [IQR] range, 124-255). A total of 5941 (1.9%) patients underwent surgery with complete handover of anesthesia care. The percentage of patients undergoing surgery with a handover of anesthesiology care progressively increased each year of the study, reaching 2.9% in 2015. In the unweighted sample, the primary outcome occurred in 44% of the complete handover group compared with 29% of the no handover group. After adjustment, complete handovers were statistically significantly associated with an increased risk of the primary outcome (adjusted risk difference [aRD], 6.8% [95% CI, 4.5% to 9.1%]; P < .001), all-cause death (aRD, 1.2% [95% CI, 0.5% to 2%]; P = .002), and major complications (aRD, 5.8% [95% CI, 3.6% to 7.9%]; P < .001), but not with hospital readmission within 30 days of surgery (aRD, 1.2% [95% CI, -0.3% to 2.7%]; P = .11).

CONCLUSIONS AND RELEVANCE

Among adults undergoing major surgery, complete handover of intraoperative anesthesia care compared with no handover was associated with a higher risk of adverse postoperative outcomes. These findings may support limiting complete anesthesia handovers.

Atypical antipsychotic drugs and the risk for acute kidney injury and other adverse outcomes in older adults: a population-based cohort study

BACKGROUND

Several adverse outcomes attributed to atypical antipsychotic drugs, specifically quetiapine, risperidone, and olanzapine, are known to cause acute kidney injury (AKI). Such outcomes include hypotension, acute urinary retention, and the neuroleptic malignant syndrome or rhabdomyolysis.

OBJECTIVE

To investigate the risk for AKI and other adverse outcomes associated with use of atypical antipsychotic drugs versus nonuse.

DESIGN

Population-based cohort study.

SETTING

Ontario, Canada, from 2003 to 2012.

PATIENTS

Adults aged 65 years or older who received a new outpatient prescription for an oral atypical antipsychotic drug (n=97,777) matched 1:1 with those who did not receive such a prescription.

MEASUREMENTS

The primary outcome was hospitalization with AKI (assessed by using a hospital diagnosis code and, in a subpopulation, serum creatinine levels) within 90 days of prescription for atypical antipsychotic drugs.

RESULTS

Atypical antipsychotic drug use versus nonuse was associated with a higher risk for hospitalization with AKI (relative risk [RR], 1.73 [95% CI, 1.55 to 1.92]). This association was consistent when AKI was assessed in a subpopulation for which information on serum creatinine levels was available (5.46% vs. 3.34%; RR, 1.70 [CI, 1.22 to 2.38]; absolute risk increase, 2.12% [CI, 0.80% to 3.43%]). Drug use was also associated with hypotension (RR, 1.91 [CI, 1.60 to 2.28]), acute urinary retention (RR, 1.98 [CI, 1.63 to 2.40]), and all-cause mortality (RR, 2.39 [CI, 2.28 to 2.50]).

LIMITATION

Only older adults were included in the study.

CONCLUSION

Atypical antipsychotic drug use is associated with an increased risk for AKI and other adverse outcomes that may explain the observed association with AKI. The findings support current safety concerns about the use of these drugs in older adults.

PRIMARY FUNDING SOURCE

Academic Medical Organization of Southwestern Ontario.

Retrieving clinical evidence: a comparison of PubMed and Google Scholar for quick clinical searches

BACKGROUND

Physicians frequently search PubMed for information to guide patient care. More recently, Google Scholar has gained popularity as another freely accessible bibliographic database.

OBJECTIVE

To compare the performance of searches in PubMed and Google Scholar.

METHODS

We surveyed nephrologists (kidney specialists) and provided each with a unique clinical question derived from 100 renal therapy systematic reviews. Each physician provided the search terms they would type into a bibliographic database to locate evidence to answer the clinical question. We executed each of these searches in PubMed and Google Scholar and compared results for the first 40 records retrieved (equivalent to 2 default search pages in PubMed). We evaluated the recall (proportion of relevant articles found) and precision (ratio of relevant to nonrelevant articles) of the searches performed in PubMed and Google Scholar. Primary studies included in the systematic reviews served as the reference standard for relevant articles. We further documented whether relevant articles were available as free full-texts.

RESULTS

Compared with PubMed, the average search in Google Scholar retrieved twice as many relevant articles (PubMed: 11%; Google Scholar: 22%; P<.001). Precision was similar in both databases (PubMed: 6%; Google Scholar: 8%; P=.07). Google Scholar provided significantly greater access to free full-text publications (PubMed: 5%; Google Scholar: 14%; P<.001).

CONCLUSIONS

For quick clinical searches, Google Scholar returns twice as many relevant articles as PubMed and provides greater access to free full-text articles.

Validity of the International Classification of Diseases, Tenth Revision code for acute kidney injury in elderly patients at presentation to the emergency department and at hospital admission

OBJECTIVE

To evaluate the validity of the International Classification of Diseases, Tenth Revision (ICD-10) code N17x for acute kidney injury (AKI) in elderly patients in two settings: at presentation to the emergency department and at hospital admission.

DESIGN

A population-based retrospective validation study.

SETTING

Southwestern Ontario, Canada, from 2003 to 2010.

PARTICIPANTS

Elderly patients with serum creatinine measurements at presentation to the emergency department (n=36 049) or hospital admission (n=38 566). The baseline serum creatinine measurement was a median of 102 and 39 days prior to presentation to the emergency department and hospital admission, respectively.

MAIN OUTCOME MEASURES

Sensitivity, specificity and positive and negative predictive values of ICD-10 diagnostic coding algorithms for AKI using a reference standard based on changes in serum creatinine from the baseline value. Median changes in serum creatinine of patients who were code positive and code negative for AKI.

RESULTS

The sensitivity of the best-performing coding algorithm for AKI (defined as a ≥2-fold increase in serum creatinine concentration) was 37.4% (95% CI 32.1% to 43.1%) at presentation to the emergency department and 61.6% (95% CI 57.5% to 65.5%) at hospital admission. The specificity was greater than 95% in both settings. In patients who were code positive for AKI, the median (IQR) increase in serum creatinine from the baseline was 133 (62 to 288) µmol/l at presentation to the emergency department and 98 (43 to 200) µmol/l at hospital admission. In those who were code negative, the increase in serum creatinine was 2 (-8 to 14) and 6 (-4 to 20) µmol/l, respectively.

CONCLUSIONS

The presence or absence of ICD-10 code N17× differentiates two groups of patients with distinct changes in serum creatinine at the time of a hospital encounter. However, the code underestimates the true incidence of AKI due to a limited sensitivity.

Use of clinical decision support systems for kidney-related drug prescribing: a systematic review

BACKGROUND

Clinical decision support systems (CDSSs) have the potential to improve kidney-related drug prescribing by supporting the appropriate initiation, modification, monitoring, or discontinuation of drug therapy.

STUDY DESIGN

Systematic review. We identified studies by searching multiple bibliographic databases (eg, MEDLINE and EMBASE), conference proceedings, and reference lists of all included studies.

SETTING & POPULATION

CDSSs used in hospital or outpatient settings for acute kidney injury and chronic kidney disease, including end-stage renal disease (chronic dialysis patients or transplant recipients).

SELECTION CRITERIA FOR STUDIES

Studies prospectively using CDSSs to aid in kidney-related drug prescribing.

INTERVENTION

Computerized or manual CDSSs.

OUTCOMES

Clinician prescribing and patient-important outcomes as reported by primary study investigators. CDSS characteristics, such as whether the system was computerized, and system setting.

RESULTS

We identified 32 studies. In 17 studies, CDSSs were computerized, and in 15 studies, they were manual pharmacist-based systems. Systems intervened by prompting for drug dosing adjustments in relation to the level of decreased kidney function (25 studies) or in response to serum drug concentrations or a clinical parameter (7 studies). They were used most in academic hospital settings. For computerized CDSSs, clinician prescribing outcomes (eg, frequency of appropriate dosing) were considered in 11 studies, with all 11 reporting statistically significant improvements. Similarly, manual CDSSs that incorporated clinician prescribing outcomes showed statistically significant improvements in 6 of 8 studies. Patient-important outcomes (eg, adverse drug events) were considered in 7 studies of computerized CDSSs, with statistically significant improvements in 2 studies. For manual CDSSs, 6 studies measured patient-important outcomes and 5 reported statistically significant improvements. Cost-savings also were reported, mostly for manual CDSSs.

LIMITATIONS

Studies were heterogeneous in design and often limited by the evaluation method used. Benefits of CDSSs may be reported selectively in this literature.

CONCLUSION

CDSSs are available for many dimensions of kidney-related drug prescribing, and results are promising. Additional high-quality evaluations will guide their optimal use.

Antibiotic Prescribing for Nonbacterial Acute Upper Respiratory Infections in Elderly Persons

BACKGROUND

Reducing inappropriate antibiotic prescribing for acute upper respiratory tract infections (AURIs) requires a better understanding of the factors associated with this practice.

OBJECTIVE

To determine the prevalence of antibiotic prescribing for nonbacterial AURIs and whether prescribing rates varied by physician characteristics.

DESIGN

Retrospective analysis of linked administrative health care data.

SETTING

Primary care physician practices in Ontario, Canada (January-December 2012).

PATIENTS

Patients aged 66 years or older with nonbacterial AURIs. Patients with cancer or immunosuppressive conditions and residents of long-term care homes were excluded.

MEASUREMENTS

Antibiotic prescriptions for physician-diagnosed AURIs. A multivariable logistic regression model with generalized estimating equations was used to examine whether prescribing rates varied by physician characteristics, accounting for clustering of patients among physicians and adjusting for patient-level covariates.

RESULTS

The cohort included 8990 primary care physicians and 185 014 patients who presented with a nonbacterial AURI, including the common cold (53.4%), acute bronchitis (31.3%), acute sinusitis (13.6%), or acute laryngitis (1.6%). Forty-six percent of patients received an antibiotic prescription; most prescriptions were for broad-spectrum agents (69.9% [95% CI, 69.6% to 70.2%]). Patients were more likely to receive prescriptions from mid- and late-career physicians than early-career physicians (rate difference, 5.1 percentage points [CI, 3.9 to 6.4 percentage points] and 4.6 percentage points [CI, 3.3 to 5.8 percentage points], respectively), from physicians trained outside of Canada or the United States (3.6 percentage points [CI, 2.5 to 4.6 percentage points]), and from physicians who saw 25 to 44 patients per day or 45 or more patients per day than those who saw fewer than 25 patients per day (3.1 percentage points [CI, 2.1 to 4.0 percentage points] and 4.1 percentage points [CI, 2.7 to 5.5 percentage points], respectively).

LIMITATION

Physician rationale for prescribing was unknown.

CONCLUSION

In this low-risk elderly cohort, 46% of patients with a nonbacterial AURI were prescribed antibiotics. Patients were more likely to receive prescriptions from mid- or late-career physicians with high patient volumes and from physicians who were trained outside of Canada or the United States.

PRIMARY FUNDING SOURCE

Ontario Ministry of Health and Long-term Care, Academic Medical Organization of Southwestern Ontario, Schulich School of Medicine and Dentistry, Western University, and Lawson Health Research Institute.

Testing, infection and complication rates of COVID-19 among people with a recent history of homelessness in Ontario, Canada: a retrospective cohort study

BACKGROUND

People with a recent history of homelessness are believed to be at high risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and, when infected, complications of coronavirus disease 2019 (COVID-19). We describe and compare testing for SARS-CoV-2, test positivity and hospital admission, receipt of intensive care and mortality rates related to COVID-19 for people with a recent history of homelessness versus community-dwelling people as of July 31, 2020.

METHODS

We conducted a population-based retrospective cohort study in Ontario, Canada, between Jan. 23 and July 31, 2020, using linked health administrative data among people who either had a recent history of homelessness or were dwelling in the community. People were included if they were eligible for provincial health care coverage and not living in an institutionalized facility on Jan. 23, 2020. We examined testing for SARS-CoV-2, test positivity and complication outcomes of COVID-19 (hospital admission, admission to intensive care and death) within 21 days of a positive test result. Extended multivariable Cox proportional hazard models were used to estimate adjusted hazard ratios (HRs) in 3 time periods: preshutdown (Jan. 23-Mar. 13), peak (Mar. 14-June 16) and reopening (June 17-July 31).

RESULTS

People with a recent history of homelessness (n = 29 407) were more likely to be tested for SARS-CoV-2 in all 3 periods compared with community-dwelling people (n = 14 494 301) (preshutdown adjusted HR 1.61, 95% confidence interval [CI] 1.22-2.11; peak adjusted HR 2.95, 95% CI 2.88-3.03; reopening adjusted HR 1.45, 95% CI 1.39-1.51). They were also more likely to have a positive test result (peak adjusted HR 3.66, 95% CI 3.22-4.16; reopening adjusted HR 1.76, 95% CI 1.15-2.71). In the peak period, people with a recent history of homelessness were over 20 times more likely to be admitted to hospital for COVID-19 (adjusted HR 20.35, 95% CI 16.23-25.53), over 10 times more likely to require intensive care for COVID-19 (adjusted HR 10.20, 95% CI 5.81-17.93) and over 5 times more likely to die within 21 days of their first positive test result (adjusted HR 5.73, 95% CI 3.01-10.91).

INTERPRETATION

In Ontario, people with a recent history of homelessness were significantly more likely to be tested for SARS-CoV-2, to have a positive test result, to be admitted to hospital for COVID-19, to receive intensive care for COVID-19 and to die of COVID-19 compared with community-dwelling people. People with a recent history of homelessness should continue to be considered particularly vulnerable to SARS-CoV-2 infection and its complications.

Disparities in surgery among patients with intractable epilepsy in a universal health system

OBJECTIVE

To assess the use of epilepsy surgery in patients with medically intractable epilepsy in a publicly funded universal health care system.

METHODS

We performed a population-based retrospective cohort study using linked health care databases for Ontario, Canada, between 2001 and 2010. We identified all patients with medically intractable epilepsy, defined as those with seizures that did not respond to at least 2 adequate trials of seizure medications. We assessed the proportion of patients who had epilepsy surgery within the following 2 years. We further identified the characteristics associated with epilepsy surgery.

RESULTS

A total of 10,661 patients were identified with medically intractable epilepsy (mean age 47 years, 51% male); most (74%) did not have other comorbidities. Within 2 years of being defined as medically intractable, only 124 patients (1.2%) underwent epilepsy surgery. Death occurred in 12% of those with medically intractable epilepsy. Those who underwent the procedure were younger and had fewer comorbidities compared to those who did not.

CONCLUSION

In our setting of publicly funded universal health care, more than 10% of patients died within 2 years of developing medically intractable epilepsy. Epilepsy surgery may be an effective treatment for some patients; however, fewer than 2% of patients who may have benefited from epilepsy surgery received it.

Trends in the age of diagnosis of childhood asthma

BACKGROUND

The cause of rising asthma incidence over time remains unexplained. Examining trends in the age of diagnosis across successive birth cohorts may offer insights into asthma etiology.

OBJECTIVE

To examine trends in the age at asthma diagnosis and the age and proportion of children hospitalized at first asthma diagnosis in Ontario, Canada.

METHODS

Eight consecutive birth cohorts of children (1993-2000) were observed using administrative data from a universal health insurance plan in Ontario, Canada (population 13 million). Trends in the need for hospitalization and age at asthma diagnosis were examined with descriptive and survival analyses.

RESULTS

The records of 1,059,511 children were examined, of whom 201,958 developed asthma in the first 8 years of life, with an average cumulative incidence of 19.1%. Mean age at asthma diagnosis decreased from 4.7 ± 1.5 years in birth year 1993 to 2.6 ± 2.0 years in birth year 2000 (P < .0001), with a higher adjusted risk of asthma diagnosis (hazard ratio, 6.7; 95% CI, 6.5-6.9) in the first 3 years of life for children born after 1996 versus children born in the period 1993 to 1995 (hazard ratio, 1.4; 95% CI, 1.3-1.4). The proportion of children hospitalized at asthma diagnosis stayed stable while the age at first asthma hospitalization decreased over time (P < .0001).

CONCLUSIONS

This study demonstrates a significant increase in asthma incidence and a decrease in the age of asthma diagnosis across multiple birth cohorts. Changes in asthma incidence over time are primarily explained by variations in asthma rates in children younger than 3 years.

Characteristics and Outcomes of AKI Treated with Dialysis during Pregnancy and the Postpartum Period

Acute kidney injury (AKI) is a rare complication of pregnancy, but may be associated with significant morbidity and mortality in young and often otherwise healthy women. We conducted a retrospective population-based cohort study of all consecutive pregnancies over a 15-year period (1997-2011) in Ontario, Canada, and describe the incidence and outcomes of AKI treated with dialysis during pregnancy or within 12 weeks of delivery. Of 1,918,789 pregnancies, 188 were complicated by AKI treated with dialysis (incidence: 1 per 10,000 [95% confidence interval, 0.8 to 1.1]). Only 21 of 188 (11.2%) women had record of a preexisting medical condition; however, 130 (69.2%) women experienced a major pregnancy-related complication, including preeclampsia, thrombotic microangiopathy, heart failure, sepsis, or postpartum hemorrhage. Eight women died (4.3% versus 0.01% in the general population), and seven (3.9%) women remained dialysis dependent 4 months after delivery. Low birth weight (<2500 g), small for gestational age, or preterm birth (<37 weeks' gestation) were more common in pregnancies in which dialysis was initiated (35.6% versus 14.0%; relative risk, 3.40; 95% confidence interval, 2.52 to 4.58). There were no stillbirths and fewer than five neonatal deaths (<2.7%) in affected pregnancies compared with 0.1% and 0.8%, respectively, in the general population. In conclusion, AKI treated with dialysis during pregnancy is rare and typically occurs in healthy women who acquire a major pregnancy-related medical condition such as preeclampsia. Many affected women and their babies have good short-term outcomes.

Validity of the International Classification of Diseases 10th revision code for hyperkalaemia in elderly patients at presentation to an emergency department and at hospital admission

OBJECTIVES

Evaluate the validity of the International Classification of Diseases, 10th revision (ICD-10) code for hyperkalaemia (E87.5) in two settings: at presentation to an emergency department and at hospital admission.

DESIGN

Population-based validation study.

SETTING

12 hospitals in Southwestern Ontario, Canada, from 2003 to 2010.

PARTICIPANTS

Elderly patients with serum potassium values at presentation to an emergency department (n=64 579) and at hospital admission (n=64 497).

PRIMARY OUTCOME

Sensitivity, specificity, positive-predictive value and negative-predictive value. Serum potassium values in patients with and without a hyperkalaemia code (code positive and code negative, respectively).

RESULTS

The sensitivity of the best-performing ICD-10 coding algorithm for hyperkalaemia (defined by serum potassium >5.5 mmol/l) was 14.1% (95% CI 12.5% to 15.9%) at presentation to an emergency department and 14.6% (95% CI 13.3% to 16.1%) at hospital admission. Both specificities were greater than 99%. In the two settings, the positive-predictive values were 83.2% (95% CI 78.4% to 87.1%) and 62.0% (95% CI 57.9% to 66.0%), while the negative-predictive values were 97.8% (95% CI 97.6% to 97.9%) and 96.9% (95% CI 96.8% to 97.1%). In patients who were code positive for hyperkalaemia, median (IQR) serum potassium values were 6.1 (5.7 to 6.8) mmol/l at presentation to an emergency department and 6.0 (5.1 to 6.7) mmol/l at hospital admission. For code-negative patients median (IQR) serum potassium values were 4.0 (3.7 to 4.4) mmol/l and 4.1 (3.8 to 4.5) mmol/l in each of the two settings, respectively.

CONCLUSIONS

Patients with hospital encounters who were ICD-10 E87.5 hyperkalaemia code positive and negative had distinct higher and lower serum potassium values, respectively. However, due to very low sensitivity, the incidence of hyperkalaemia is underestimated.

Risk of adverse events among older adults following co-prescription of clarithromycin and statins not metabolized by cytochrome P450 3A4

BACKGROUND

The cytochrome P450 3A4 (CYP3A4) inhibitor clarithromycin may also inhibit liver-specific organic anion-transporting polypeptides (OATP1B1 and OATP1B3). We studied whether concurrent use of clarithromycin and a statin not metabolized by CYP3A4 was associated with an increased frequency of serious adverse events.

METHODS

Using large health care databases, we studied a population-based cohort of older adults (mean age 74 years) who were taking a statin not metabolized by CYP3A4 (rosuvastatin [76% of prescriptions], pravastatin [21%] or fluvastatin [3%]) between 2002 and 2013 and were newly prescribed clarithromycin (n=51,523) or azithromycin (n=52,518), the latter an antibiotic that inhibits neither CYP3A4 nor OATP1B1 and OATP1B3. Outcomes were hospital admission with a diagnostic code for rhabdomyolysis, acute kidney injury or hyperkalemia, and all-cause mortality. All outcomes were assessed within 30 days after co-prescription.

RESULTS

Compared with the control group, patients co-prescribed clarithromycin and a statin not metabolized by CYP3A4 were at increased risk of hospital admission with acute kidney injury (adjusted relative risk [RR] 1.65, 95% confidence interval [CI] 1.31 to 2.09), admission with hyperkalemia (adjusted RR 2.17, 95% CI 1.22 to 3.86) and all-cause mortality (adjusted RR 1.43, 95% CI 1.15 to 1.76). The adjusted RR for admission with rhabdomyolysis was 2.27 (95% CI 0.86 to 5.96). The absolute increase in risk for each outcome was small and likely below 1%, even after we considered the insensitivity of some hospital database codes.

INTERPRETATION

Among older adults taking a statin not metabolized by CYP3A4, co-prescription of clarithromycin versus azithromycin was associated with a modest but statistically significant increase in the 30-day absolute risk of adverse outcomes.

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.

Validation study of health administrative data algorithms to identify individuals experiencing homelessness and estimate population prevalence of homelessness in Ontario, Canada

OBJECTIVES

To validate case ascertainment algorithms for identifying individuals experiencing homelessness in health administrative databases between 2007 and 2014; and to estimate homelessness prevalence trends in Ontario, Canada, between 2007 and 2016.

DESIGN

A population-based retrospective validation study.

SETTING

Ontario, Canada, from 2007 to 2014 (validation) and 2007 to 2016 (estimation).

PARTICIPANTS

Our reference standard was the known housing status of a longitudinal cohort of housed (n=137 200) and homeless or vulnerably housed (n=686) individuals. Two reference standard definitions of homelessness were adopted: the housing episode and the annual housing experience (any homelessness within a calendar year).

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive and negative predictive values and positive likelihood ratios of 30 case ascertainment algorithms for detecting homelessness using up to eight health service databases.

RESULTS

Sensitivity estimates ranged from 10.8% to 28.9% (housing episode definition) and 18.5% to 35.6% (annual housing experience definition). Specificities exceeded 99% and positive likelihood ratios were high using both definitions. The most optimal algorithm estimates that 59 974 (95% CI 55 231 to 65 208) Ontarians (0.53% of the adult population) experienced homelessness in 2016, a 67.3% increase from 2007.

CONCLUSIONS

In Ontario, case ascertainment algorithms for identifying homelessness had low sensitivity but very high specificity and positive likelihood ratio. The use of health administrative databases may offer opportunities to track individuals experiencing homelessness over time and inform efforts to improve housing and health status in this vulnerable population.

First-Ever Ischemic Stroke and Incident Major Adverse Cardiovascular Events in 93 627 Older Women and Men

Background and Purpose- Stroke risk is sex-specific, but little is known about sex differences of poststroke major adverse cardiovascular events (MACEs). Stroke-related brain damage causes autonomic dysfunction and inflammation, sometimes resulting in cardiac complications. Sex-specific cardiovascular susceptibility to stroke without the confounding effect of preexisting heart disease constitutes an unexplored field because previous studies focusing on sex differences in poststroke MACE have not excluded patients with known cardiovascular comorbidities. We therefore investigated sex-specific risks of incident MACE in a heart disease-free population-based cohort of patients with first-ever ischemic stroke and propensity-matched individuals without stroke. Methods- We included Ontario residents ≥66 years, without known cardiovascular comorbidities, with first-ever ischemic stroke between 2002 and 2012 and propensity-matched individuals without stroke. We investigated the 1-year risk of incident MACE (acute coronary syndrome, myocardial infarction, incident coronary artery disease, coronary revascularization procedures, incident heart failure, or cardiovascular death) separately for females and males. For estimating cause-specific adjusted hazard ratios, we adjusted Cox models for variables with weighted standardized differences >0.10 or those known to influence MACE risk. Results- We included 93 627 subjects without known cardiovascular comorbidities; 21 931 with first-ever ischemic stroke and 71 696 propensity-matched subjects without stroke. Groups were well-balanced on propensity-matching variables. There were 53 476 women (12 421 with and 41 055 without ischemic stroke) and 40 151 men (9510 with and 30 641 without ischemic stroke). First-ever ischemic stroke was associated with increased risk of incident MACE in both sexes. The risk was time-dependent, highest within 30 days (women: adjusted hazard ratio, 25.1 [95% CI, 19.3-32.6]; men: aHR, 23.4 [95% CI, 17.2-31.9]) and decreasing but remaining significant between 31 and 90 days (women: aHR, 4.8 [95% CI, 3.8-6.0]; men: aHR, 4.2 [95% CI, 3.3-5.4]), and 91 to 365 days (aHR, 2.1 [95% CI, 1.8-2.3]; men: aHR, 2.0 [95% CI, 1.7-2.3]). Conclusions- In this large population-based study, ischemic stroke was independently associated with increased risk of incident MACE in both sexes.

Hyponatremia and sodium picosulfate bowel preparations in older adults

OBJECTIVES

Bowel preparations are commonly prescribed drugs. Case reports and our clinical experience suggest that sodium picosulfate bowel preparations can precipitate severe hyponatremia in some older adults. At present, this risk is poorly quantified. We investigated the association between sodium picosulfate use and the risk of hyponatremia in older adults.

METHODS

We conducted a population-based retrospective cohort study using six linked administrative databases in Ontario, Canada. All Ontario residents over the age of 65 years who filled an outpatient bowel preparation prescription before colonoscopy were eligible. We enrolled new users of either sodium picosulfate (n=99,237) or polyethylene glycol (n=48,595). The primary outcome was hospitalization with hyponatremia within 30 days of the bowel preparation assessed by database codes. The secondary outcomes were hospitalization with urgent head computed tomography (CT) (a proxy for acute central nervous system disturbance) and all-cause mortality.

RESULTS

The baseline characteristics of the two groups, including patient demographics, comorbid conditions, and concomitant medications, were nearly identical. Compared with polyethylene glycol, sodium picosulfate was associated with a higher risk of hospitalization with hyponatremia (absolute risk increase: 0.05%, 95% confidence interval (CI): 0.04-0.06%, relative risk (RR): 2.4, 95% CI: 1.5-3.9), but not hospitalization with urgent CT head (RR: 1.1, 95% CI: 0.7-1.4) or mortality (RR: 0.9, 95% CI: 0.7-1.3).

CONCLUSIONS

Sodium picosulfate bowel preparations lead to more hyponatremia than polyethylene glycol. There was no evidence of increased risk of acute neurologic symptoms or mortality. The absolute increase in risk of hospitalization with hyponatremia remains low but may be avoidable through appropriate fluid intake or preferential use of polyethylene glycol in some older adults.

Complications of daytime elective laparoscopic cholecystectomies performed by surgeons who operated the night before

IMPORTANCE

The effect of surgeons' disrupted sleep on patient outcomes is not clearly defined.

OBJECTIVE

To assess if surgeons operating the night before have more complications of elective surgery performed the next day.

DESIGN, SETTING, AND PARTICIPANTS

Population-based, matched, retrospective cohort study using administrative health care databases in Ontario, Canada (2012 population, 13,505,900). Participants were 2078 patients who underwent elective laparoscopic cholecystectomies performed by surgeons who operated the night before, matched with 4 other elective laparoscopic cholecystectomy recipients (n = 8312).

EXPOSURE

In total, 94,183 eligible elective laparoscopic cholecystectomies were performed between 2004 and 2011. Of these surgeries, there were 2078 procedures in which 331 different surgeons across 102 community hospitals had operated between midnight and 7 am the night before. Each "at-risk" surgery was randomly matched with 4 other elective laparoscopic cholecystectomies (n = 8312) performed by the same surgeon, who had no evidence of having operated the night before.

MAIN OUTCOMES AND MEASURES

The primary outcome was conversion from a laparoscopic cholecystectomy to open cholecystectomy. Secondary outcomes included evidence of iatrogenic injuries or death. Risks were quantified using generalized estimating equations.

RESULTS

No significant association was found in conversion rates to open operations between surgeons when they operated the night before compared with when they did not operate the previous night (46/2031 [2.2%] vs 157/8124 [1.9%]; adjusted odds ratio [OR], 1.18; 95% CI, 0.85-1.64). There was no association between operating the night before vs not operating the night before, and risk of iatrogenic injuries (14/2031 [0.7%] vs 72/8124 [0.9%]; adjusted OR, 0.77; 95% CI, 0.43-1.37) or death (≤5/2031 [≤0.2%] vs 7/8124 [0.1%]).

CONCLUSIONS AND RELEVANCE

No significant association was found between operating the night before and not operating the previous night for conversion to open cholecystectomy, risk of iatrogenic complications, or death for elective daytime cholecystectomy. These findings do not support safety concerns related to surgeons operating the night before performing elective surgery.

Risks of preoperative anemia in women undergoing elective hysterectomy and myomectomy

BACKGROUND

Hysterectomy is one of the most common surgeries performed worldwide. Identification of modifiable risk factors for complications or readmissions could lead to targeted interventions to improve patient care and reduce health care costs. Preoperative anemia has been identified as a risk factor for adverse postoperative outcomes following noncardiac surgery. However, studies have not focused on young and healthy surgical populations, such as women undergoing gynecologic surgery for benign indications.

OBJECTIVE

The purpose of this study was to evaluate whether preoperative anemia in women undergoing elective hysterectomy or myomectomy for benign indications was associated with increased 30 day postoperative morbidity and mortality.

STUDY DESIGN

In this retrospective, population-based cohort study, we followed up adult women (≥18 years of age) who underwent elective hysterectomy or myomectomy (laparoscopic/laparotomy) between the years 2013 and 2015 for benign indications in Ontario, Canada. We used linked administrative data from a government-administered, single-payer provincial health care system using Canadian Classification of Health Interventions intervention codes, International Classification of Diseases, 10th revision, diagnostic codes, physician billing codes, and laboratory data from both community and hospital laboratories across the province. Our exposure of interest was preoperative anemia, defined as a hemoglobin value <12 g/dL on the complete blood count measured closest to the date of surgery. Our primary outcome was the composite of 30 day postoperative morbidity and mortality. Secondary outcomes were 5 individual components of the primary outcome: death, transfusion, surgical site infection, venothromboembolism, and return to the hospital within 30 days. To adjust for confounding, we generated a propensity score using a multiple logistic regression model in which the presence of anemia was regressed on all baseline characteristics. We matched anemic to nonanemic patients on the logit of the propensity score. Using an unadjusted log-binomial model estimated using generalized estimating equations to account for the matched pairs, we calculated the relative risk, 95% confidence intervals, and P values to evaluate the effect of anemia on outcomes.

RESULTS

Of the 16,218 women in the cohort, 3664 (22.6%) had anemia. After propensity matching, standardized differences in all baseline characteristics (n = 3261 per group) were <0.10. In the matched cohort, the primary outcome (death, complications, or readmission) occurred in 41.2% of anemic patients and 36.2% of nonanemic patients (relative risk, 1.14, 95% confidence interval, 1.07-1.21, P < .0001; absolute risk reduction, 5.03%, 95% confidence interval, 2.70-7.36; (number needed to harm = 20). The risk of transfusion was significantly higher in anemic patients (relative risk, 3.25, 95% confidence interval, 2.67-3.95, P < .0001; absolute risk reduction, 8.34%, 95% confidence interval, 7.06-9.63; number needed to harm = 12). There was no difference in other secondary outcomes. In a subgroup analysis (women >55 years vs ≤55, n = 736), older women were at increased risk of the primary outcome (relative risk, 1.40, 95% confidence interval, 1.12-1.76, P = .004), transfusion (relative risk, 4.20, 95% confidence interval, 1.65-10.72, P = .003), surgical site infection (relative risk, 1.35, 95% confidence interval, 1.01-1.81, P = .04), and return to the hospital (relative risk, 2.36, 95% confidence interval, 1.54-3.62, P < .0001).

CONCLUSION

Preoperative anemia in women undergoing elective hysterectomy/myomectomy was common and is an independent risk factor for 30 day postoperative adverse outcomes, especially in older women.

Youth Mental Health Services Utilization Rates After a Large-Scale Social Media Campaign: Population-Based Interrupted Time-Series Analysis

BACKGROUND

Despite the uptake of mass media campaigns, their overall impact remains unclear. Since 2011, a Canadian telecommunications company has operated an annual, large-scale mental health advocacy campaign (Bell Let's Talk) focused on mental health awareness and stigma reduction. In February 2012, the campaign began to explicitly leverage the social media platform Twitter and incented participation from the public by promising donations of Can $0.05 for each interaction with a campaign-specific username (@Bell_LetsTalk).

OBJECTIVE

The intent of the study was to examine the impact of this 2012 campaign on youth outpatient mental health services in the province of Ontario, Canada.

METHODS

Monthly outpatient mental health visits (primary health care and psychiatric services) were obtained for the Ontario youth aged 10 to 24 years (approximately 5.66 million visits) from January 1, 2006 to December 31, 2015. Interrupted time series, autoregressive integrated moving average modeling was implemented to evaluate the impact of the campaign on rates of monthly outpatient mental health visits. A lagged intervention date of April 1, 2012 was selected to account for the delay required for a patient to schedule and attend a mental health-related physician visit.

RESULTS

The inclusion of Twitter into the 2012 Bell Let's Talk campaign was temporally associated with an increase in outpatient mental health utilization for both males and females. Within primary health care environments, female adolescents aged 10 to 17 years experienced a monthly increase in the mental health visit rate from 10.2/1000 in April 2006 to 14.1/1000 in April 2015 (slope change of 0.094 following campaign, P<.001), whereas males of the same age cohort experienced a monthly increase from 9.7/1000 to 9.8/1000 (slope change of 0.052 following campaign, P<.001). Outpatient psychiatric services visit rates also increased for both male and female adolescents aged 10 to 17 years post campaign (slope change of 0.005, P=.02; slope change of 0.003, P=.005, respectively). For young adults aged 18 to 24 years, females who used primary health care experienced the most significant increases in mental health visit rates from 26.5/1000 in April 2006 to 29.2/1000 in April 2015 (slope change of 0.17 following campaign, P<.001).

CONCLUSIONS

The 2012 Bell Let's Talk campaign was temporally associated with an increase in the rate of mental health visits among Ontarian youth. Furthermore, there appears to be an upward trend of youth mental health utilization in the province of Ontario, especially noticeable in females who accessed primary health care services.

Home Mechanical Ventilation: A 12-Year Population-Based Retrospective Cohort Study

BACKGROUND

Increasing numbers of individuals are being initiated on home mechanical ventilation, including noninvasive (bi-level) and invasive mechanical ventilation delivered via tracheostomy due to chronic respiratory failure to enable symptom management and promote quality of life. Given the high care needs of these individuals, a better understanding of the indications for home mechanical ventilation, and health-care utilization is needed.

METHODS

We performed a retrospective cohort study using provincial health administrative data from Ontario, Canada (population ∼13,000,000). Home mechanical ventilation users were characterized using health administrative data to determine the indications for home mechanical ventilation, the need for acute care at the time of ventilation approval, and their health service use and mortality rates following approval.

RESULTS

The annual incidence of home mechanical ventilation approval rose from 1.8/100,000 in 2000 to 5.0/100,000 in 2012, or an annual increase of approximately 0.3/100,000 persons/y. The leading indications were neuromuscular disease, thoracic restriction, and COPD. The indication for the remainder could not be determined due to limitations of the administrative databases. Of the 4,670 individuals, 23.0% commenced home mechanical ventilation following an acute care hospitalization. Among individuals who survived at least 1 y, fewer required hospitalization in the year that followed home mechanical ventilation approval (29.9% vs 39.8%) as compared with the year prior.

CONCLUSIONS

Utilization of home mechanical ventilation is increasing in Ontario, Canada, and further study is needed to clarify the factors contributing to this and to further optimize utilization of health-care resources.

Beyond the grey tsunami: a cross-sectional population-based study of multimorbidity in Ontario

OBJECTIVES

To determine volumes and rates of multimorbidity in Ontario by age group, sex, material deprivation, and geography.

METHODS

A cross-sectional population-based study was completed using linked provincial health administrative databases. Ontario residents were classified as having multimorbidity (3+ chronic conditions) or not, based on the presence of 17 chronic conditions. The volumes (number of residents) of multimorbidity were determined by age categories in addition to crude and age-sex standardized rates.

RESULTS

Among the 2013 Ontario population, 15.2% had multimorbidity. Multimorbidity rates increased across successively older age groups with lowest rates observed in youngest (0-17 years, 0.2%) and highest rates in the oldest (80+ years, 73.5%). The rate of multimorbidity increased gradually from ages 0 to 44 years, with a substantial and graded increase in the rates as the population aged. The top five chronic conditions, of the 17 examined, among those with multimorbidity were mood disorders, hypertensive disorders, asthma, arthritis, and diabetes.

CONCLUSION

Much of the common rhetoric around multimorbidity concerns the aging 'grey tsunami'. This study demonstrated that the volume of multimorbidity is derived from adults beginning as young as age 35 years old. A focus only on the old underestimates the absolute burden of multimorbidity on the health care system. It can mask the association of material deprivation and geography with multimorbidity which can turn our attention away from two critical issues: (1) potential inequality in health and health care in Ontario and (2) preventing younger and middle-aged people from moving into the multimorbidity category.