Positive Predictive Values of International Classification of Diseases, 10th Revision Coding Algorithms to Identify Patients With Autosomal Dominant Polycystic Kidney Disease

Data driven approach to characterize rapid decline in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic kidney disease with high phenotypic variability. Furthering insights into patients' ADPKD progression could lead to earlier detection, management, and alter the course to end stage kidney disease (ESKD). We sought to identify patients with rapid decline (RD) in kidney function and to determine clinical factors associated with RD using a data-driven approach. A retrospective cohort study was performed among patients with incident ADPKD (1/1/2002-12/31/2018). Latent class mixed models were used to identify RD patients using differences in eGFR trajectories over time. Predictors of RD were selected based on agreements among feature selection methods, including logistic, regularized, and random forest modeling. The final model was built on the selected predictors and clinically relevant covariates. Among 1,744 patients with incident ADPKD, 125 (7%) were identified as RD. Feature selection included 42 clinical measurements for adaptation with multiple imputations; mean (SD) eGFR was 85.2 (47.3) and 72.9 (34.4) in the RD and non-RD groups, respectively. Multiple imputed datasets identified variables as important features to distinguish RD and non-RD groups with the final prediction model determined as a balance between area under the curve (AUC) and clinical relevance which included 6 predictors: age, sex, hypertension, cerebrovascular disease, hemoglobin, and proteinuria. Results showed 72%-sensitivity, 70%-specificity, 70%-accuracy, and 0.77-AUC in identifying RD. 5-year ESKD rates were 38% and 7% among RD and non-RD groups, respectively. Using real-world routine clinical data among patients with incident ADPKD, we observed that six variables highly predicted RD in kidney function.

Kidney Stones Account for Increased Imaging Studies in Autosomal Dominant Polycystic Kidney Disease

Key Points

Kidney stones are common in patients with autosomal dominant polycystic kidney disease compared with matched controls with CKD. The increase in imaging seen in patients with autosomal dominant polycystic kidney disease correlates with the kidney stone burden in these patients.

Background

Patients with autosomal dominant polycystic kidney disease (ADPKD) may have more imaging studies than patients with other forms of CKD. We characterized the imaging burden of patients with ADPKD relative to a CKD population to determine which factors lead to increased imaging in patients with ADPKD.

Methods

We retrospectively reviewed patients seen at Yale Nephrology between January 2012 and January 2021. We collected demographic, clinical, and imaging data through automated query and manual chart review. Eight hundred seven patients with ADPKD were matched to 4035 CKD controls on the basis of criteria of sex, race, ethnicity, CKD stage, hypertension, and diabetes, but not age. The number of abdominal imaging studies were compared between ADPKD and CKD groups, and the effect of kidney stone diagnosis was further evaluated. Chi-square and t tests were used to evaluate demographic variables, and Kruskal Wallis and negative binomial regression models were used to evaluate differences between abdominal imaging studies.

Results

Patients with ADPKD had a greater number of total abdominal imaging studies (P < 0.0001), ultrasounds (P < 0.0001), and magnetic resonance imagings (P = 0.02) compared with controls. In patients with preserved renal function (eGFR >60 ml/min per m2), these differences persisted. Kidney stones were significantly more common among patients with ADPKD (P < 0.0001). In multivariable assessment of imaging study counts using a negative binomial model controlling for kidney stones, ADPKD was no longer a significant predictor. In patients with ADPKD, pyelonephritis; cyst complications; lower eGFR; diabetes; coronary artery disease; kidney stones; lower body mass index; and being male, Black, and younger increased the likelihood of having more imaging studies.

Conclusions

The higher prevalence of abdominal imaging studies in patients with ADPKD correlated with the increased incidence of kidney stones observed in this population.

A Computable Phenotype for Autosomal Dominant Polycystic Kidney Disease

Background

A computable phenotype is an algorithm used to identify a group of patients within an electronic medical record system. Developing a computable phenotype that can accurately identify patients with autosomal dominant polycystic kidney disease (ADPKD) will assist researchers in defining patients eligible to participate in clinical trials and other studies. Our objective was to assess the accuracy of a computable phenotype using International Classification of Diseases 9th and 10th revision (ICD-9/10) codes to identify patients with ADPKD.

Methods

We reviewed four random samples of approximately 250 patients on the basis of ICD-9/10 codes from the EHR from the Kansas University Medical Center database: patients followed in nephrology clinics who had ICD-9/10 codes for ADPKD (Neph+), patients seen in nephrology clinics without ICD codes for ADPKD (Neph-), patients who were not followed in nephrology clinics with ICD codes for ADPKD (No Neph+), and patients not seen in nephrology clinics without ICD codes for ADPKD (No Neph-). We reviewed the charts and determined ADPKD status on the basis of internationally accepted diagnostic criteria for ADPKD.

Results

The computable phenotype to identify patients with ADPKD who attended nephrology clinics has a sensitivity of 99% (95% confidence interval [95% CI], 96.4 to 99.7) and a specificity of 84% (95% CI, 79.5 to 88.1). For those who did not attend nephrology clinics, the sensitivity was 97% (95% CI, 93.3 to 99.0), and a specificity was 82% (95% CI, 77.4 to 86.1).

Conclusion

A computable phenotype using the ICD-9/10 codes can correctly identify most patients with ADPKD, and can be utilized by researchers to screen health care records for cohorts of patients with ADPKD with acceptable accuracy.

Risk of Hospital Encounters With Kidney Stones in Autosomal Dominant Polycystic Kidney Disease: A Cohort Study

Background:

There is a perception that patients with autosomal dominant polycystic kidney disease (ADPKD) are more likely to develop kidney stones than the general population.

Objective:

To compare the rate of hospital encounter with kidney stones and the rate of stone interventions between patients with and without ADPKD.

Design:

Retrospective cohort study.

Setting:

Ontario, Canada.

Patients:

Patients with and without ADPKD who had a prior hospital encounter between 2002 and 2016.

Measurements:

Rate of hospital encounter with kidney stones and rate of stone intervention.

Methods:

We used inverse probability exposure weighting based on propensity scores to balance baseline indicators of health between patients with and without ADPKD. We followed each patient until death, emigration, outcomes, or March 31, 2017. We used a Cox proportional hazards model to compare event rates between the two groups.

Results:

Patients with ADPKD were at higher risk of hospital encounter with stones compared with patients without ADPKD (81 patients of 2094 with ADPKD [3.8%] vs 60 patients of 1902 without ADPKD [3.2%]; 8.9 vs 5.1 events per 1000 person-years; hazard ratio 1.6 [95% CI, 1.3-2.1]). ADPKD was not associated with a higher risk of stone intervention (49 of 2094 [2.3%] vs 47 of 1902 [2.4%]; 5.3 vs 3.9 events per 1000 person-years; hazard ratio 1.2 [95% CI = 0.9-1.3]).

Limitations:

We did not have information on kidney stone events outside of the hospital. There is a possibility of residual confounding.

Conclusion:

ADPKD was a significant risk factor for hospital encounters with kidney stones.

Complications in Patients With Autosomal Dominant Polycystic Kidney Disease Undergoing Ureteroscopy: A Cohort Study

BACKGROUND

Ureteroscopy is a minimally invasive treatment option for upper tract stones. The distorted kidney anatomy in patients with autosomal dominant polycystic kidney disease (ADPKD) may place them at higher risk for ureteroscopic complications.

OBJECTIVE

To compare the 30-day risk of ureteroscopic complications between patients with and without ADPKD.

DESIGN

Retrospective cohort study.

SETTING

Ontario, Canada.

PATIENTS

Seventy three patients with ADPKD and 81 445 patients without ADPKD who underwent ureteroscopy for upper urinary tract stones between April 1, 2002, and March 1, 2018.

MEASUREMENTS

A 30-day risk of (1) hospital presentation with ureteroscopic complications (which was a composite outcome of either emergency department visit or hospital admission with acute kidney injury, urinary tract infection, or sepsis); (2) all-cause hospital presentation; (3) all-cause hospital admission; and (4) all-cause emergency department visit.

METHODS

We regressed outcomes on demographic variables, health care use in the prior 1-year, various procedures and comorbidities related to the outcome in the prior 5 years, and prescribed medications filled in the past 120 days using modified Poisson regression to compare the risk ratio (RR) of each outcome between patients with and without ADPKD.

RESULTS

The median (interquartile, IQR) age was 44 (38-60 years) in the ADPKD group and 53 (42-64) in the control group. About 40% were women in both groups. The risk of ureteroscopic complications was not significantly different in patients with versus without ADPKD (8.2% vs 4.3%; adjusted RR = 1.5, 95% confidence interval [CI] = 0.7-3.2). Patients with versus without ADPKD were more likely to present to hospital after their procedure (35.6% vs. 20.0%; adjusted RR = 1.6, 95% CI = 1.2-2.2), which included a statistically significant increase in the risk of presenting to the emergency department (32.9% vs. 19.0%; adjusted RR = 1.6, 95% CI = 1.1-2.2) but not hospital admissions (10.9% vs. 5.0%; adjusted RR = 1.8, 95% CI = 0.9-3.4).

LIMITATIONS

The low numbers of events led to imprecision around the estimates.

CONCLUSION

Patients with ADPKD have a higher risk of return to the hospital within 30 days of ureteroscopy for stone disease.

TRIAL REGISTRATION

We did not register this study.

Diagnostic accuracy of administrative codes for autosomal dominant polycystic kidney disease in clinic patients with cystic kidney disease

Background

The ability to identify patients with autosomal dominant polycystic kidney disease (ADPKD) and distinguish them from patients with similar conditions in healthcare administrative databases is uncertain. We aimed to measure the sensitivity and specificity of different ADPKD administrative coding algorithms in a clinic population with non-ADPKD and ADPKD kidney cystic disease.

Methods

We used a dataset of all patients who attended a hereditary kidney disease clinic in Toronto, Ontario, Canada between 1 January 2010 and 23 December 2014. This dataset included patients who met our reference standard definition of ADPKD or other cystic kidney disease. We linked this dataset to healthcare databases in Ontario. We developed eight algorithms to identify ADPKD using the International Classification of Diseases, 10th Revision (ICD-10) codes and provincial diagnostic billing codes. A patient was considered algorithm positive if any one of the codes in the algorithm appeared at least once between 1 April 2002 and 31 March 2015.

Results

The ICD-10 coding algorithm had a sensitivity of 33.7% [95% confidence interval (CI) 30.0–37.7] and a specificity of 86.2% (95% CI 75.7–92.5) for the identification of ADPKD. The provincial diagnostic billing code had a sensitivity of 91.1% (95% CI 88.5–93.1) and a specificity of 10.8% (95% CI 5.3–20.6).

Conclusions

ICD-10 coding may be useful to identify patients with a high chance of having ADPKD but fail to identify many patients with ADPKD. Provincial diagnosis billing codes identified most patients with ADPKD and also with other types of cystic kidney disease.

Analysis of Nationwide Data to Determine the Incidence and Diagnosed Prevalence of Autosomal Dominant Polycystic Kidney Disease in the USA: 2013-2015

BACKGROUND

This study addresses an important gap, as it is the first US nationwide, epidemiologic study of ADPKD incidence and prevalence.

SUMMARY

This 3-year, observational study utilized data from Truven Health MarketScan® administrative claims, as well as cross-sectional data from the National Ambulatory Medical Care Survey (NAMCS). We estimated the annual incidence and diagnosed prevalence using population-based data on over 170 million de-identified patients to provide the most current epidemiologic estimates available. The ADPKD-diagnosed prevalence was 4.3 per 10,000 in the NAMCS, which closely corresponded with age-adjusted rates from patients with either commercial insurance or employer-sponsored Medicare supplemental insurance. The annual incidence was 0.62 per 10,000. Both nationwide data sets indicate that approximately 140,000 patients are currently diagnosed in the USA. We also found significant differences by gender and age. Females are nearly twice as likely as males to be diagnosed in early adulthood, while the incidence in males was highest in those aged 65 years or older. ADPKD appears more likely to be diagnosed in men after disease progression or the development of chronic kidney disease.

KEY MESSAGES

Our results revealed striking age and gender differences in the incidence of ADPKD. Young women are diagnosed with ADPKD at nearly twice the rate of young men, perhaps due to the use of ultrasound in women during child-bearing years. This points to a need for increased recognition of ADPKD, with an emphasis on younger men in particular. ADPKD has been inaccurately perceived as a common condition based on misinterpretation of early epidemiologic data (1957) confirmed by our data and recent European data. ADPKD affects approximately 140,000 patients in the USA and meets the criterion for a rare disease. Our results indicate a need for further study of gender and ADPKD diagnosis, progression, management, and outcomes.

Validity of administrative data in identifying complex surgical site infections from a population-based cohort after primary hip and knee arthroplasty in Alberta, Canada

BACKGROUND

Surgical site infections (SSIs) are a substantial burden to healthcare systems in North America. Administrative data is one method though which these may be identified, but the accuracy of using such data is uncertain.

METHODS

We followed a population-based cohort of patients who received primary hip/knee arthroplasty in Alberta, Canada, for whom a comprehensive Infection Prevention and Control (IPC) prospective surveillance methodology was used to track SSIs. Patients were also followed using International Classification of Diseases, Tenth Revision (ICD-10) codes. We assessed the sensitivity/specificity and positive/negative predictive values of ICD-10 codes compared to IPC surveillance.

RESULTS

Between April 1, 2012, and March 31, 2015, 24,512 people received hip/knee arthroplasty. Of these, 258 (1.05%) had a complex SSI found by IPC surveillance. Sensitivity and specificity of ICD-10 codes in identifying complex SSIs after hip/knee arthroplasty were 85.3% (95% confidence interval [CI] 80.3%-89.4%) and 99.5% (95% CI 99.4%-99.6%), respectively. Positive and negative predictive values were 63.6% (95% CI 58.3%-68.7%) and 99.8% (95% CI 99.8%-99.9%), respectively.

DISCUSSION

Administrative data have reasonable testing characteristics for identifying complex SSIs after arthroplasty. For centers without prospective surveillance programs, this could be useful in identifying hospitals with frequent complex SSIs after arthroplasty.

CONCLUSIONS

A comprehensive IPC surveillance program is superior at detecting SSIs after arthroplasty.