Development and validation of a case definition to estimate the prevalence and incidence of cirrhosis in pan-Canadian primary care databases

Screening and Diagnosis of Chronic Kidney Disease in Adults Living With Diabetes: A Retrospective Cohort Study Using the Canadian Primary Care Sentinel Surveillance Network

OBJECTIVES

In Canada, regional evaluations of screening practices for chronic kidney disease (CKD) among people with diabetes highlight areas for improvement; however, national estimates are notably absent. Estimates of CKD incidence often discount the expected decline in estimated glomerular filtration rate (eGFR) associated with age; age-adaptive thresholds may help account for this. We describe the frequency of screening and diagnosis of CKD among adults with diabetes from a nationally representative primary care cohort.

METHODS

In this retrospective cohort study, we used electronic medical record data from the Canadian Primary Care Sentinel Surveillance Network. We followed adult patients (≥18 years of age) with diabetes without CKD at baseline for 5 years starting in 2014. We determined the frequency of urine albumin-to-creatinine ratio (uACr) and/or eGFR testing over time. We identified incident CKD diagnoses based on eGFR measurements using fixed-threshold and age-adaptive definitions and quantified the incidence proportion and rate.

RESULTS

We analyzed records from 37,604 patients with diabetes. Only 13% of patients had yearly eGFR and uACr testing for CKD, although roughly 60% had non-yearly use of both tests in 5 years. eGFR testing was performed more frequently than uACr testing (94.1% vs 76.6% having testing over follow-up). We found increased incidence proportions (14.6% vs 6.0%) and rates (33.1 vs 13.4 diagnoses per 1,000 person-years) of CKD using the fixed-threshold compared with age-adaptive definition.

CONCLUSIONS

Our study presents the first national understanding of screening practices for CKD among people with diabetes in Canada. Specifically, increased use of uACr testing should be encouraged for early detection of changes in kidney function.

Identifying patients with diagnosed cirrhosis in administrative health databases: a validation study

Objectives

Case ascertainment algorithms were developed and validated to identify people living with cirrhosis in administrative health data in Manitoba, Canada using primary care electronic medical records (EMR) to define the reference standards.

Methods

We linked provincial administrative health data to primary care EMR data. The validation cohort included 116,675 Manitobans aged >18 years with at least one primary care visit between April 1998 and March 2015. Hospital records, physician billing claims, vital statistics, and prescription drug data were used to develop and test 93 case-finding algorithms. A validated case definition for primary care EMR data was the reference standard. We estimated sensitivity, specificity, positive and negative predictive values (PPV, NPV), Youden's index, area under the receiver operative curve, and their 95% confidence intervals (CIs).

Results

A total of 116,675 people were in the validation cohort. The prevalence of cirrhosis was 1.4% (n = 1593). Algorithm sensitivity estimates ranged from 32.5% (95% CI 32.2-32.8) to 68.3% (95% CI 68.0-68.9) and PPV from 17.4% (95% CI 17.1-17.6) to 23.4% (95% CI 23.1-23.6). Specificity (95.5-98.2) and NPV (approximately 99%) were high for all algorithms. The algorithms had slightly higher sensitivity estimates among men compared with women, and individuals aged ≥45 years compared to those aged 18-44 years.

Conclusion

Cirrhosis algorithms applied to administrative health data had moderate validity when a validated case definition for primary care EMRs was the reference standard. This study provides algorithms for identifying diagnosed cirrhosis cases for population-based research and surveillance studies.