Background: Young adults (18-39 years old) have the lowest rates of hypertension control compared to middle-aged and older adults. Shorter follow-up encounter intervals have been associated with faster rates of hypertension control in middle-aged and older adults. However, the optimal follow-up interval is not defined in younger adults. The objective was to evaluate the relationship between ambulatory follow-up intervals, defined as the average number of provider-patient blood pressure encounters over time, and rates of hypertension control among young adults with incident hypertension.
Methods: This was a retrospective analysis of 3,150 young adults receiving regular primary care in a large, Midwestern, academic group practice from 2008-2011. Patients were included upon meeting JNC7 clinical criteria for hypertension (≥140/90 mmHg) and followed for 24 months. Young adults with a previous hypertension diagnosis or prior antihypertensive medication were excluded. We calculated the average blood pressure encounter interval over 24 months and categorized the intervals using established categories of <1 month, 1-2 months, 2-3 months, 3-6 months, and >6 month intervals. Summary statistics were constructed using frequencies and proportions for categorical data and median (25th, 75th percentile) for continuous variables. Univariate associations between continuous variables were assessed using two-sided t-test. The probability of achieving hypertension control (<140/90 mmHg) for patients within each encounter interval category was estimated by Kaplan-Meier analysis.
Results: Among young adults with newly diagnosed hypertension (59% male, 83% White), those with the shortest average encounter interval (<1 month) were more likely to be female, have Stage 1 (mild) hypertension, Medicaid use, diabetes mellitus, and mental health diagnoses (all p<0.007). The likelihood of achieving hypertension control within 24 months was greater for shorter encounter intervals: <1 month (91%), 1-2 months (76%), 2-3 months (65%), 3-6 months (40%), and >6 months (13%), p<0.001. Respectively, the median time in months to hypertension control (25th-75th percentile) by encounter intervals was: 2.8 (1.8-3.9), 7.1 (5.1-11.3), 10.5 (8.5-14.4), 16.4 (12.4-22.6), and 23.9 (22.5-24.1) months. Young adults with 2-3 month and 3-6 month encounter intervals had higher rates of antihypertensive medication initiation within 24 months, 28% (884/3150) and 27% (850/3150) respectively, compared to 21% (661/3150) with <1 month visit interval.
Conclusions: A shorter encounter interval (<1 month) is associated with higher and faster rates of hypertension control within 24 months among young adults with incident hypertension. Sustainable interventions to support shorter follow-up intervals between young adults and primary care teams are needed to improve rates and timeliness of hypertension control.