Predictors of adherence to inhaled medications among Veterans with COPD.
BACKGROUND
Factors contributing to medication nonadherence among patients with chronic obstructive pulmonary disease (COPD) are poorly understood.


OBJECTIVE
To identify patient characteristics that are predictive of adherence to inhaled medications for COPD and, for patients on multiple inhalers, to assess whether adherence to one medication class was associated with adherence to other medication classes.


METHODS
Cohort study using data from Veteran Affairs (VA) electronic databases.


METHODS
This study included 2,730 patients who underwent pulmonary function testing between 2003 and 2007 at VA facilities in the Northwestern United States, and who met criteria for COPD.


METHODS
We used pharmacy records to estimate adherence to inhaled corticosteroids (ICS), ipratropium bromide (IP), and long-acting beta-agonists (LABA) over two consecutive six month periods. We defined patients as adherent if they had refilled medications to have 80 % of drug available over the time period. We also collected information on their demographics, behavioral habits, COPD severity, and comorbidities.


RESULTS
Adherence to medications was poor, with 19.8 % adherent to ICS, 30.6 % adherent to LABA, and 25.6 % adherent to IP. Predictors of adherence to inhaled therapies were highly variable and dependent on the medication being examined. In adjusted analysis, being adherent to a medication at baseline was the strongest predictor of future adherence to that same medication [(Odds ratio, 95 % confidence interval) ICS: 4.78 (3.21-7.11); LABA: 6.56 (3.89-11.04); IP: 13.96 (9.88-19.72)], [corrected] but did not reliably predict adherence to other classes of medications. [corrected].


CONCLUSIONS
Among patients with COPD, past adherence to one class of inhaled medication strongly predicted future adherence to the same class of medication, but only weakly predicted adherence to other classes of medication.
Health Services Research and Development, VA Puget Sound Health Care System, 1100 Olive Way, Suite 1400, Seattle, WA, 98101, USA.
John C
JC
Huetsch
Jane E
JE
Uman
Edmunds M
EM
Udris
David H
DH
Au
D000280:Administration, Inhalation; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use*; D058666:Adrenergic beta-2 Receptor Agonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D009241:Ipratropium / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D055118:Medication Adherence / Q000523:psychology*; D008875:Middle Aged; D015205:Northwestern United States; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy*; D014728:Veterans
D000305:Adrenal Cortex Hormones; D058666:Adrenergic beta-2 Receptor Agonists; D009241:Ipratropium