Potentially inappropriate primary care prescribing in people with chronic kidney disease: a cross-sectional analysis of a large population cohort

Background: Many drugs should be avoided or require dose-adjustment in chronic kidney disease (CKD). Previous estimates of potentially inappropriate prescribing rates have been based on data on a limited number of drugs, and mainly in secondary care settings.

Aim: To determine the prevalence of contraindicated and potentially inappropriate primary care prescribing in a complete population of people with known CKD.

Design and setting: Cross-sectional study of prescribing patterns in a complete geographical population of people with CKD, defined using laboratory data.

Method: Drugs were organised by British National Formulary advice - contraindicated drugs: 'avoid'; potentially high-risk (PHR) drugs: 'avoid if possible'; and dose-inappropriate (DI) drugs: 'dose exceeded recommended maximums'. CKD was defined as estimated glomerular filtration rate (eGFR) ≤60 ml/min/1.73 m² for >3 months.

Results: In total, 28 489 people with CKD were included in the analysis, of whom 70.1% had CKD stage 3a, 22.4% CKD stage 3b, 5.9% CKD stage 4, and 1.5% CKD stage 5. A total of 3.9% (95% confidence interval [CI] = 3.7 to 4.1) of people with CKD stages 3a-5 were prescribed ≥1 contraindicated drug, 24.3% (95% CI = 23.8 to 24.8) ≥1 PHR drug, and 15.2% (95% CI = 14.8 to 15.6) ≥1 DI drug. Contraindicated drugs differed in prevalence by CKD stage and were most commonly prescribed in CKD stage 4, with a prevalence of 36.0% (95% CI = 33.7 to 38.2). PHR drugs were commonly prescribed in all CKD stages, ranging from 19.4% (95% CI = 17.6 to 21.3) in CKD stage 4 to 25.1% (95% CI = 24.5 to 25.7) in CKD stage 3a. DI drugs were most commonly prescribed in CKD stage 4 (26.4%, 95% CI = 24.3 to 28.6).

Conclusion: Potentially inappropriate prescribing is common at all stages of CKD. Development and evaluation of interventions to improve prescribing safety in this high-risk population are needed.