BACKGROUND: Therapy with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) requires laboratory monitoring to avoid hyperkalemia and acute kidney failure.
OBJECTIVE: To assess the frequency of recommended annual serum potassium and creatinine monitoring and determine potential factors associated with care gaps among adults dispensed an ACEI or ARB.
METHODS: This mixed-methods study integrated findings from a retrospective cohort study and individual patient interviews. Adults aged 21 years and over within Kaiser Permanente Southern California with at least 180 treatment days of an ACEI and/or ARB in 2015 were included. Patients invited for qualitative interviews included those who did and did not complete the recommended laboratory tests. We assessed the proportion of patients completing both recommended laboratory tests, factors associated with not receiving laboratory monitoring, and patients' insights into barriers and facilitators of recommended monitoring.
RESULTS: Of 437,544 patients who received an ACEI or ARB, 9.0% did not receive both a serum potassium and creatinine laboratory test during treatment (defined as a care gap). Lower risk of a care gap was observed for patients with increasing age (rate ratio [RR] per 10-year increase = 0.78, 95% CI = 0.77-0.79); diabetes mellitus (RR = 0.62, 95% CI = 0.60-0.64); hypertension (RR = 0.71, 95% CI = 0.71-0.74); Charlson Comorbidity Index score of at least 2 (RR = 0.62, 95% CI = 0.60-0.64); those who changed medication classes (RR = 0.53, 95% CI = 0.51-0.56); and patients with a cardiologist (RR = 0.81, 95% CI = 0.73-0.90) or nephrologist (RR = 0.60, 95% CI = 0.52-0.69) as their prescribing provider. Twenty-five patients completed the qualitative interviews. Patients often lacked knowledge about the need for laboratory monitoring, cited logistical barriers to accessing the laboratory, and deemed the reminders they received through an outpatient safety program as a facilitator to completing tests.
CONCLUSIONS: Given the large patient population on ACEI and ARB medications, monitoring and support strategies such as electronic clinical surveillance could be important in addressing care gaps and potentially reducing adverse drug effects.