Depression Worsens Outcomes in Chronic Stable Angina

After diagnosis of chronic stable angina, depression can occur in approximately 1 in 5 patients, according to a retrospective population-based cohort study published in Circulation.¹

While previous studies have observed a link between depression and worse prognosis in patients with myocardial infarction (MI), not much is known about depression in patients with chronic stable angina. The incidence of depression after MI has been reported to be between 10% and 40%, and is associated with adverse outcomes.^2-4 In addition, patients with post-MI depression have a 1.6-fold to 2.7-fold increased risk of new cardiac events, cardiac mortality, and all-cause mortality within 24 months.⁵ 

Natalie Szpakowski, MD, of the Schulich Heart Centre at Sunnybrook Health Sciences Center in Toronto, and colleagues developed multivariable Cox proportional hazards models to identify predictors of depression in patients with stable angina. All-cause mortality, hospital admission for MI, and subsequent revascularization were the main clinical outcomes.

Out of 22,917 patients, 4305 (18.8%) were found to have experienced depression over a mean follow-up of 1084 days. Nearly 85% of these patients were identified as having depression by family physicians compared with 8.1% who were identified by psychiatrists. Depression was identified in 8% of patients within 30 days, 10.3% between 30 and 90 days, 10.4% between 90 and 180 days, and 16.9% between 180 and 365 days; the remainder of patients experienced a depressive episode beyond 1 year after their index angiogram.

The researchers found that the strongest predictor of developing depression was an episode of depression within the past 10 years (hazard ratio [HR]: 1.88; 95% confidence interval [CI], 1.75-2.02). Female sex, higher Charlson score, being a current smoker, and increasing Canadian Cardiovascular Society (CCS) angina class were also considered factors that increased risk of depression. Conversely, living in rural areas and older age were both associated with lower likelihood of having depression (HR: 0.81; 95% CI, 0.73-0.90; P <.001 and HR: 0.89; 95% CI, 0.82-0.96; P =.002, respectively).

Patients with depression had higher rates of unadjusted all-cause mortality vs those without (7.6% vs 6.4%; P =.005), as well as MI admissions (4.7% vs 2.8%; P <.001) and subsequent revascularization (14% vs 10.7%; P <.001). Depression was associated with an 83% increased hazard of death (HR: 1.83; 95% CI, 1.62-2.07; P <.001) and was significantly associated with MI admission (HR: 1.36; 95% CI, 1.10-1.67; P =.005) in the fully adjusted model. However, depression did not appear to affect the need for subsequent revascularization (HR: 1.13; 95% CI, 0.99-1.28; P =.07).

These study findings were consistent with the current literature on depression, according to the authors. “In particular, it is important to recognize the importance of a previous, remote history of depression, which was the strongest predictor of a subsequent occurrence, reinforcing the remitting and relapsing nature of depression.” In addition, they found no significant link between initial treatment strategy and depression, which implies that revascularization does not prevent future risk of depression.

Study Limitations

A misclassification bias may have occurred due to depression being defined more broadly for the purposes of this study (ie, patients with depression outside of the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition criteria for major depressive disorder were also included in this cohort). Including said patients may have inflated the occurrence of depression as well as diluted the outcomes. However, the researchers noted, “with this inclusive definition, the presence of depression as we defined it was, nonetheless, significantly predictive of all-cause mortality and admission for MI.”

Another limitation may be that residual survivorship tends to bias to the null, in that patients who died early in the study were not classified as having depression, thereby underestimating the impact of depression.

References

1. Szpakowski N, Bennell MC, Qiu F, et al. Clinical impact of subsequent depression in patients with a new diagnosis of stable angina. A population-based study. Circulation. 2016 October 4. doi:10.1161/CIRCOUTCOMES.116.002904 [Epub ahead of print].
2. Thombs BD, Bass EB, Ford DE, et al. Prevalence of depression in survivors of acute myocardial infarction. J Gen Intern Med. 2006;21:30-38. doi:10.1111/j.1525-1497.2005.00269.x.
3. Kaptein KI, de Jonge P, van den Brink RH, Korf J. Course of depressive symptoms after myocardial infarction and cardiac prognosis: a latent class analysis. Psychosom Med. 2006;68:662-668. doi:10.1097/01.psy.0000233237.79085.57.
4. Mallik S, Spertus JA, Reid KJ, et al; for the PREMIER Registry Investigators. Depressive symptoms after acute myocardial infarction: evidence for highest rates in younger women. Arch Intern Med. 2006;166:876-883. doi:10.1001/archinte.166.8.876.
5. Meijer A, Conradi HJ, Bos EH, et al. Prognostic association of depression following myocardial infarction with mortality and cardiovascular events: a meta-analysis of 25 years of research. Gen Hosp Psychiatry. 2011;33:203-216. doi:10.1016/j.genhosppsych.2011.02.007.