Sociodemographic and clinical characteristics are not clinically useful predictors of refill adherence in patients with hypertension.
BACKGROUND
Although many studies have identified patient characteristics or chronic diseases associated with medication adherence, the clinical utility of such predictors has rarely been assessed. We attempted to develop clinical prediction rules for adherence with antihypertensive medications in 2 healthcare delivery systems.


RESULTS
We performed retrospective cohort studies of hypertension registries in an inner-city healthcare delivery system (n=17 176) and a health maintenance organization (n=94 297) in Denver, Colo. Adherence was defined by acquisition of 80% or more of antihypertensive medications. A multivariable model in the inner-city system found that adherent patients (36.3% of the total) were more likely than nonadherent patients to be older, white, married, and acculturated in US society, to have diabetes or cerebrovascular disease, not to abuse alcohol or controlled substances, and to be prescribed fewer than 3 antihypertensive medications. Although statistically significant, all multivariate odds ratios were 1.7 or less, and the model did not accurately discriminate adherent from nonadherent patients (C statistic=0.606). In the health maintenance organization, where 72.1% of patients were adherent, significant but weak associations existed between adherence and older age, white race, the lack of alcohol abuse, and fewer antihypertensive medications. The multivariate model again failed to accurately discriminate adherent from nonadherent individuals (C statistic=0.576).


CONCLUSIONS
Although certain sociodemographic characteristics or clinical diagnoses are statistically associated with adherence to refills of antihypertensive medications, a combination of these characteristics is not sufficiently accurate to allow clinicians to predict whether their patients will be adherent with treatment.
Steiner
John F
JF
Colorado Health Outcomes Program, the Department of Family Medicine, University of Colorado, Denver, CO, USA. john.f.steiner@kp.org
Ho
P Michael
PM
Beaty
Brenda L
BL
Dickinson
L Miriam
LM
Hanratty
Rebecca
R
Zeng
Chan
C
Tavel
Heather M
HM
Havranek
Edward P
EP
Davidson
Arthur J
AJ
Magid
David J
DJ
Estacio
Raymond O
RO
D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D003120:Colorado / Q000453:epidemiology; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D005260:Female; D006279:Health Maintenance Organizations / Q000706:statistics & numerical data; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology* / Q000517:prevention & control; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D012042:Registries; D012189:Retrospective Studies; D012959:Socioeconomic Factors; D019037:Urban Health Services / Q000706:statistics & numerical data; D016903:Drug Monitoring
D000959:Antihypertensive Agents