Clinic Visit Timing, Prescribing Patterns, and Antihypertensive Medication Adherence: Evidence from Linked U.S. Electronic Health Records and Pharmacy Data

Abstract

Introduction: Medication adherence is critical for hypertension management but remains suboptimal. Most interventions target patient-level barriers, while routine care factors, such as the timing of clinic visits, remain underexamined. Time-of-day effects on clinical decision-making are documented in acute care, but implications for chronic disease management are less understood.

Methods: A longitudinal analysis of 936,502 U.S. adults with hypertension receiving 4,027,607 antihypertensive prescriptions (2016-2024) linked electronic health records with pharmacy dispensing data. Associations between appointment hour and prescription filling and 90-day medication adherence (proportion of days covered ≥80%) were estimated. Secondary outcomes included visit duration, days' supply, and fixed-dose combination prescribing. Models adjusted for patient, clinician, and visit characteristics with month and year fixed effects. Analyses were conducted in 2025.

Results: Compared with 7 AM visits, 5 PM visits had 10.6% lower odds of adherence (adjusted odds ratio [AOR]: 0.894; 95% CI: 0.854-0.935) and 8.8% lower odds of prescription filling (AOR: 0.912; 95% CI: 0.871-0.954). Each hour later was associated with 1.0% lower odds of adherence (AOR: 0.990; 95% CI: 0.988-0.992) and 0.9% lower odds of filling (AOR: 0.991; 95% CI: 0.989-0.993). Later visits were associated with shorter visit durations, fewer days' supply per fill, and less fixed-dose combination prescribing. Time-of-day patterns appeared only for filled prescriptions, consistent with an association linked to prescribing-dispensing processes rather than patient characteristics.

Conclusions: Later visit times were associated with lower prescription filling and adherence, as well as shorter visits, reduced medication supply, and less fixed-dose combination prescribing. These patterns suggest prescribing and dispensing processes vary by time-of-day. Attention to consistent medication management practices throughout the clinic day may help reduce this variation.

Keywords: anti-hypertensive; clinical decision making; duty hours/work hours; medication adherence; primary care.