Table 3.
Unadjusted and multivariable adjusted relative risk and 95% confidence intervals for low adherence to antihypertensive medication among Medicare beneficiaries in 2007–2012, excluding beneficiaries who discontinued treatment.
| Characteristic | Unadjusted RR (95% CI) |
Multivariable Adjusted 1 RR (95% CI) |
Multivariable Adjusted 2 RR (95% CI) |
|---|---|---|---|
| Calendar year* | |||
| 2007 | 1(ref) | 1(ref) | 1(ref) |
| 2008 | 0.96 (0.91–1.01) | 0.97 (0.92–1.02) | 0.97 (0.92–1.01) |
| 2009 | 0.97 (0.93–1.02) | 0.99 (0.94–1.04) | 0.99 (0.94–1.04) |
| 2010 | 0.94 (0.89–0.99) | 0.96 (0.92–1.01) | 0.96 (0.91–1.01) |
| 2011 | 0.89 (0.84–0.93) | 0.93 (0.88–0.97) | 0.92 (0.87–0.97) |
| 2012 | 0.85 (0.80–0.89) | 0.89 (0.84–0.93) | 0.88 (0.83–0.92) |
| Age, years | |||
| 65–69 | 1(ref) | 1(ref) | 1(ref) |
| 70–74 | 1.03 (0.98–1.07) | 1.03 (0.99–1.07) | 1.03 (0.98–1.07) |
| 75–79 | 1.02 (0.97–1.06) | 1.03 (0.98–1.07) | 1.02 (0.98–1.07) |
| 80–84 | 0.98 (0.94–1.03) | 1.02 (0.97–1.07) | 1.01 (0.96–1.06) |
| 85+ | 0.93 (0.88–0.98) | 1.00 (0.95–1.05) | 0.99 (0.94–1.04) |
| Sex | |||
| Male | 1(ref) | 1(ref) | 1(ref) |
| Female | 0.97 (0.94–1.00) | 0.96 (0.93–0.99) | 0.96 (0.93–0.99) |
| Race/ethnicity | |||
| White | 1(ref) | 1(ref) | 1(ref) |
| Black | 1.37 (1.31–1.43) | 1.37 (1.31–1.44) | 1.36 (1.30–1.43) |
| Hispanic | 1.50 (1.41–1.61) | 1.37 (1.28–1.47) | 1.37 (1.28–1.47) |
| Asian | 1.21 (1.11–1.32) | 1.10 (1.01–1.21) | 1.11 (1.02–1.22) |
| Other | 1.21 (1.11–1.32) | 1.18 (1.08–1.29) | 1.18 (1.09–1.29) |
| Antihypertensive drug class initiated |
|||
| Thiazide-type diuretic | 1.05 (1.01–1.08) | 1.10 (1.05–1.15) | 1.09 (1.04–1.15) |
| Calcium channel blocker | 0.82 (0.80–0.85) | 0.85 (0.82–0.89) | 0.86 (0.82–0.89) |
| Angiotensin converting enzyme inhibitor |
0.83 (0.79–0.86) | 0.87 (0.84–0.90) | 0.86 (0.84–0.89) |
| Angiotensin receptor blocker |
1.13 (1.09–1.17) | 1.10 (1.06–1.15) | 1.11 (1.06–1.15) |
| Loop diuretic | 1.18 (1.12–1.23) | 1.33 (1.26–1.39) | 1.34 (1.28–1.41) |
| Beta blocker | 0.89 (0.86–0.92) | 0.95 (0.92–0.99) | 0.96 (0.92–0.99) |
| Other | 0.96 (0.91–1.02) | 1.01 (0.95–1.07) | 1.01 (0.96–1.07) |
| Single/Multiclass | |||
| Single Class | 1(ref) | 1(ref) | 1(ref) |
| Multiclass/multiple pill | 0.65 (0.62–0.69) | 0.65 (0.61–0.69) | 0.67 (0.63–0.71) |
| Multiclass/Combination therapy |
1.00 (0.96–1.04) | 1.01 (0.97–1.05) | 1.01 (0.97–1.05) |
| Initiated with a 90 day fill | 0.77 (0.74–0.80) | 0.78 (0.76–0.82) | 0.78 (0.75–0.81) |
| Year before initiation | |||
| Medicaid buy-in | 1.21 (1.17–1.25) | 1.10 (1.06–1.14) | 1.11 (1.07–1.15) |
| Dementia | 0.76 (0.72–0.81) | 0.73 (0.69–0.78) | 0.76 (0.71–0.80) |
| Diabetes | 1.04 (1.01–1.08) | 1.02 (0.99–1.05) | 1.04 (1.01–1.08) |
| Coronary heart disease | 1.03 (0.99–1.07) | 1.07 (1.03–1.11) | 1.08 (1.04–1.13) |
| Stroke | 0.87 (0.81–0.92) | 0.88 (0.82–0.94) | 0.89 (0.83–0.95) |
| Chronic kidney disease | 1.02 (0.97–1.07) | 1.03 (0.99–1.08) | 1.05 (1.00–1.10) |
| Heart failure | 0.94 (0.89–0.99) | 0.97 (0.92–1.03) | 0.99 (0.94–1.05) |
| History of depression | 0.99 (0.96–1.02) | 1.01 (0.97–1.04) | 1.03 (0.99–1.07) |
| Falls | 0.92 (0.86–0.99) | 1.00 (0.93–1.07) | 1.02 (0.95–1.10) |
| Polypharmacy | 1.14 (1.10–1.18) | 1.14 (1.09–1.18) | 1.11 (1.06–1.16) |
| Medicare part D coverage gap |
0.99 (0.95–1.02) | 0.92 (0.88–0.96) | 0.89 (0.85–0.93) |
| Six months after initiation | |||
| Medicaid buy-in | 0.91 (0.82–1.01) | 0.98 (0.88–1.08) | |
| Newly diagnosed dementia | 1.03 (0.93–1.13) | 0.98 (0.89–1.08) | |
| Newly diagnosed diabetes | 1.05 (0.95–1.17) | 1.06 (0.95–1.17) | |
| Newly diagnosed coronary heart disease |
0.99 (0.92–1.07) | 1.01 (0.94–1.09) | |
| Newly diagnosed stroke | 1.12 (1.01–1.24) | 1.11 (1.00–1.23) | |
| Newly diagnosed chronic kidney disease |
1.02 (0.94–1.10) | 1.04 (0.97–1.13) | |
| Newly diagnosed heart failure |
1.10 (0.89–1.35) | 1.11 (0.89–1.38) | |
| Newly diagnosed depression | 0.94 (0.88–1.00) | 1.02 (0.96–1.09) | |
| Falls | 1.25 (1.14–1.38) | 1.31 (1.19–1.44) | |
| Polypharmacy | 0.76 (0.72–0.80) | 0.83 (0.78–0.87) | |
| Medicare part D coverage gap |
0.72 (0.67–0.78) | 0.74 (0.69–0.80) |
RR=relative risk; CI=confidence interval.
Low adherence was defined as an interval-based proportion of days covered<80% during the 365 day follow-up period among beneficiaries who did not discontinue treatment.
Multiclass=Incident prescription fill for ≥2 medications within 7 days.
Multivariable Adjusted 1–includes calendar year, age, race/ethnicity, sex, antihypertensive drug class initiated, and Medicaid buy-in, dementia, diabetes, coronary heart disease, stroke, chronic kidney disease, heart failure, history of depression, falls, polypharmacy, Medicare part D coverage gap from the year prior to antihypertensive medication initiation.
Multivariable Adjusted 2–includes variables in Model 1 and variables from the six months after antihypertensive medication initiation.
To avoid co-linearity, each antihypertensive medication class was evaluated in separate regression models with beneficiaries initiating an antihypertensive medication class being compared to beneficiaries initiating treatment without that class.
P-trend unadjusted <0.001; multivariable adjusted 1 <0.001; multivariable adjusted 2 <0.001