Rationale: Diabetes and hypertension are common among patients with airflow limitation and contribute to cardiovascular (CV) mortality, one of the leading causes of death among patients with airflow limitation. Objectives: Our goal was to examine the association of severity of airflow limitation with adherence to medications for hypertension and diabetes. Methods: We identified 7,359 veterans with hypertension and/or diabetes in the Veterans Integrated Service Network-20. Entry date into the cohort was defined as the date of a patient's first pulmonary function testing (PFT). Diagnostic codes (ICD-9), PFT, and pharmacy data were available via the electronic medical record or via direct interrogation of PFT equipment. Our primary exposure was airflow limitation defined as FEV1 ≥80% predicted (normal), 80 > FEV1 ≥50% predicted (mild/moderate), 50 > FEV1 ≥30% predicted (severe), and FEV1 < 30% predicted (very severe). We assessed adherence using a validated method based on electronic pharmacy refill data and defined adherence as ≥80% medication possession for the period 6-12 months after enrollment. Medications of interest included b-blockers, calcium channel blockers, thiazides, and angiotensin-converting-enzyme inhibitors for patients with hypertension, and metformin and sulfonylureas for patients with diabetes. We used logistic regression models to assess the association between severity of airflow limitation and adherence, adjusted for demographics, health behaviors, and comorbidities. Measurements and Main Results: Overall adherence was poor (44.6-55.1%).Among patients with hypertension,when compared with subjects with normal FEV1, subjects with each category lower of FEV1 were less adherent to b-blockers, with an odds ratio (OR) of 0.87 (95% confidence interval [CI], 0.80-0.95); calcium channel blockers, with an OR of 0.83 (95% CI, 0.74-0.93); and angiotensinconverting-enzyme inhibitors with an OR of 0.91 (95% CI, 0.84-0.99). Airflow limitation was not associated with adherence to thiazides. Among patients with diabetes, we found no significant association of FEV1 with adherence, although a similar lower trend with increasing airflow limitation. In a sensitivity analysis limited to patients with chronic obstructive pulmonary disease, we found a nonstatistically significant trend for decreased adherence to b-blockers, calcium channel blockers, and angiotensin-converting-enzyme inhibitors in subjects with higher GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage. Conclusions: Severity of airflow limitation is associated with decreased adherence to b-blockers, calcium channel blockers, and angiotensin-converting-enzyme inhibitors. The decreased adherence to these medications may be related to adverse effects on symptoms in patients with lung disease, and may partially explain excess CV mortality in these patients.
- Pulmonary function tests