The baseline characteristics of the study population are presented in . The participants who were depressed at baseline were younger, more likely to be Caucasian, exercise less and have slightly lower blood pressure readings. We also show the characteristics of the participants who met our entry criterion but did not return for the second examination. These lost to follow-up participants did not have important differences in blood pressure levels but were notably poorer, less well insured and less likely to be of European descent. Baseline depressive symptoms were more common among those participants lost to follow-up (19%) as compared to participants who remained in the study (16%).
Table 1 Descriptive statistics for the baseline characteristics of the 3185 participants from the Multi-Ethnic Study of Atherosclerosis with no anti-hypertensive medication use at either exam 1 or exam 2 based on depressive symptoms status; depressive symptoms (more ...)
The difference in SBP blood pressure attributable to depressive symptoms was small regardless of the approach used to handle untreated blood pressure, as seen in . The estimate of the association of depressive symptoms with SBP at exam 2, unadjusted for covariates other than baseline SBP, was 2.16 mmHG (95% Confidence Interval (CI): 0.04 to 4.29) and, adjusted for candidate confounders, was 2.45 mmHG (95% CI: 0.15 to 4.67). Both naïve restriction (1.91 mmHG; 95% CI: 0.49 to 3.13) and censored normal regression (1.92 mmHG; 95% CI: 0.63 to 3.21) approaches gave similar adjusted results.
Table 2 Association of Depression (anti-depressant medication use or Center for Epidemiological Studies Depression score ≥ 16) with Exam 2 Systolic Blood Pressure (adjusted linear regression model) in the Multi-Ethnic Study of Atherosclerosis using three (more ...)
The estimates of the association of depressive symptoms with DBP blood pressure were smaller and less uniformly significant than those observed for SBP, as seen in . The estimate of the association of depressive symptoms with DBP at exam 2, unadjusted for covariates other than baseline DBP, was 0.93 mmHG (95% CI—0.30 to 2.17) and, adjusted for candidate confounders, was 0.82 mmHG (95% CI: −0.62 to 2.27). Both naïve restriction (0.71 mmHG; 95% CI: 0.04 to 1.39) and censored normal regression (0.91 mmHG; 95% CI: 0.27 to 1.55) approaches gave similar adjusted results suggesting that all approaches gave reasonably consistent estimates of blood pressure associations in the presence of treatment.
Table 3 Association of Depression (anti-depressant medication use or Center for Epidemiological Studies Depression score ≥ 16) with Exam 2 Diastolic Blood Pressure (adjusted linear regression model) in the Multi-Ethnic Study of Atherosclerosis using three (more ...)
Based on the JNC7 definition of hypertension, there were 3130 participants who met the entry criteria for the incident hypertension analysis of whom 409 (12%) developed incident hypertension between the first and second exam. The main definition of hypertension (JNC7) showed no statistically significant association between depressive symptoms and incident hypertension [Relative Risk (RR): 1.02; 95% CI: 0.99 to 1.05] when adjusted for variable thought to be the most critical confounders. This estimate was unchanged (RR: 1.02; 95% CI: 0.98 to 1.06) when we expanded the pool of covariates to include: age, sex, ethnicity, smoking alcohol use, diabetes, body mass index, exercise (intentional and sedentary), Spielberger anxiety and anger scores, health insurance, income and baseline systolic and diastolic blood pressure
Use of the Davidson et al.
] definition of incident hypertension resulted in no association between baseline depressive symptoms and incident hypertension (RR: 1.01; 95% CI: 0.98 to 1.04). After adjustment for potential risk factors, there is a small association between baseline depressive symptoms and incident hypertension using the very liberal definition of either SBP 130, DBP 80 or anti-hypertensive medication (RR: 1.05; 95% CI: 1.01 to 1.08) but the importance of this association is unclear. Considering the main definition of hypertension over a different time period (between the baseline exam and the third follow-up exam, five years later) also did not yield a statistically significant association despite longer follow-up (RR 1.03; 95% CI: 0.99 to 1.07).
As a post-hoc analysis, we considered the individual components of our operational definition of depressive symptoms. shows the association of the individual components of our composite depressive symptoms endpoint with changes in blood pressure. Here CES-D is used as a continuous covariate but the inference would be the same with a dichotomous cut-point of 16 for depressive symptoms. shows the association of the individual components of our composite depressive symptoms endpoint with incident hypertension (JNC7 defintion). These components were separated into: tricyclic antidepressant use, non-tricyclic antidepressant use and CES-D score. Neither non-tricyclic antidepressant use nor CES-D score was significantly associated with incident hypertension. However, tricyclic antidepressant use was associated with incident hypertension, even after the application of a full Bonferroni adjustment for multiple comparisons (p=0.03). Restriction of the sample to the 220 antidepressant users (182 non-tricyclic antidepressant users, 27 tricyclic antidepressant users, 11 users of both agents) is an approach that may partially control for antidepressant indication (and thus reduce confounding by indication) as all participants would have had an indication for medication use. In this restricted sample of 220 participants we observed an association between tricyclic antidepressant use (RR: 1.21; 95% CI: 1.04 to 1.42) and incident hypertension using non-tricyclic antidepressants as reference (adjusting for age, sex, ethnicity and CES-D score).
Table 4 Association of individual markers of depression with blood pressure among 3911 participants in the Multi-Ethnic Study of Atherosclerosis with no baseline anti-hypertensive medication use; change is between exam 1 and exam 2 and all estimates are done (more ...)
Association of individual markers of depression with Incident Hypertension (JNC7 definition; n=409) among 3130 participants in the Multi-Ethnic Study of Atherosclerosis between exam 1 and exam 2
We tested for interactions between both ethnicity and sex with baseline depressive symptoms when estimating the relative risk of incident hypertension. There was no observed interaction between depressive symptoms and Asian (p=0.43), African-American (p=0.59) or Hispanic (p=0.78) descent. Nor was there an interaction between male sex and depressive symptoms (p=0.15). We show the estimates of this association when stratified by ethnicity in . We could not test for tricyclic effects by ethnicity as most tricyclic users were of European descent (there were 4 users of African descent, 2 users of Asian descent, 24 users of European descent and 8 users of Hispanic descent). We also noted that a 10 point change in either the Spielberger anger (RR: 0.99; 95% CI:0.95 to 1.03) or anxiety (RR: 1.01; 95% CI: 0.98 to 1.05) scores was not associated with incident hypertension (using the JNC7 definition) in this cohort.
Association of Depression (anti-depressant medication use or Center for Epidemiological Studies Depression score ≥ 16) with incident Hypertension by ethnicity; participants with baseline hypertension are excluded