Major depression in individuals with chronic medical disorders: prevalence, correlates and association with health resource utilization, lost productivity and functional disability

Abstract

Objective

The objective of this study was to determine the prevalence and odds of major depression and the incremental effect of major depression on utilization, lost productivity and functional disability in individuals with common chronic medical disorders.

Method

Data on 30,801 adults from the 1999 National Health Interview Survey were analyzed. The 12-month prevalence and age/sex-adjusted odds of major depression were calculated for adults with hypertension (HTN), diabetes mellitus (DM), coronary artery disease (CAD), congestive heart failure (CHF), stroke or cerebrovascular accident (CVA), chronic obstructive pulmonary disease (COPD) and end-stage renal disease (ESRD). The association between chronic condition status (with and without major depression) and utilization, lost productivity and functional disability was determined by controlling for covariates.

Results

The 12-month prevalence and age/sex-adjusted odds of major depression by chronic conditions were as follows: CHF, 7.9% [odds ratio (OR)=1.96]; HTN, 8.0% (OR=2.00); DM, 9.3% (OR=1.96); CAD, 9.3% (OR=2.30); CVA, 11.4% (OR=3.15); COPD, 15.4% (OR=3.21); ESRD, 17.0% (OR=3.56); any chronic condition, 8.8% (OR=2.61). Compared to adults without chronic conditions, those with chronic conditions plus major depression had greater odds of ≥1 ambulatory visit [OR=1.50; 95% confidence interval (95% CI)=1.28, 1.77]; ≥1 emergency room visit (OR=1.94; 95% CI=1.55, 2.45); and ≥1 day in bed due to illness (OR=1.60; 95% CI=1.28, 2.00); and functional disability (OR=2.48; 95% CI=1.96, 3.15).

Conclusion

The 12-month prevalence and odds of major depression are high in individuals with chronic medical conditions, and major depression is associated with significant increases in utilization, lost productivity and functional disability.

Introduction

Chronic diseases are the leading cause of death and disability in the United States, accounting for 7 of every 10 deaths and affecting the quality of life of 90 million Americans [1]. Five chronic medical disorders — heart disease, cancer, stroke or cerebrovascular accident (CVA), chronic obstructive pulmonary disease (COPD) and diabetes mellitus (DM) — account for more than two thirds of all deaths in the United States [1]. These chronic disorders cause major limitations in activity for >1 of every 10 Americans and account for 75% of health care costs in the United States [1].

Major depression affects approximately 9.9 million or 5% of the adult US population [2] and is a major cause of morbidity, mortality and disability [3], [4]. Major depression is also a major cause of work place absenteeism, diminished or lost productivity and increased use of health care resources [5]. Studies have shown that depression co-occurs in a substantial proportion of patients with various chronic medical conditions, including hypertension (HTN) [6], coronary artery disease (CAD) [7], DM [8], [9], CVA [10], [11], end-stage renal disease (ESRD) [12], [13], COPD [14], [15] and congestive heart failure (CHF) [16], [17]. However, few studies have used national population samples to establish the prevalence of depression across multiple chronic medical conditions. More importantly, few studies have examined the incremental effect of coexisting major depression on health resource utilization, lost productivity or disability beyond that attributable to the presence of a chronic medical disorder.

Although some studies have examined the effect of depression on health utilization and function in people with chronic medical conditions [18], [19], [20], these studies have major limitations that affect generalizability to the general population. For example, the study of Pyne et al. [18] was conducted in 161 veterans and assessed depression with a rating scale. In the study of Unutzer et al. [19], the sample comprised older adults (≥65 years) in a primary care setting, and depression was assessed by a rating scale. The study of Noel et al. [20] was conducted in elderly patients (≥60 years) enrolled in a clinical trial, and the major outcome was quality of life.

The main purpose of this study is to use a large nationally representative population sample to establish the prevalence of depression across common chronic medical conditions and to examine the incremental effect of coexisting major depression on health resource utilization, lost productivity and disability beyond that attributable to the presence of a chronic medical disorder. The strengths of this study include the following: (a) a large population-based sample; (b) the use of diagnostic interviews for the diagnosis of depression; (c) the inclusion of all adult age groups (≥18 years); (d) the ability to assess multiple aspects of utilization, lost productivity and functional disability in the same sample; and (e) adequate sample size to include seven chronic medical conditions that are associated with a high prevalence of coexisting depression.

Data from the 1999 National Health Interview Survey (NHIS) were analyzed to provide answers to the following important questions:

• What are the population prevalence and odds of depression across common chronic medical conditions?

• What is the incremental effect of coexisting major depression on health resource utilization, lost productivity and disability in individuals with common chronic medical disorders?

• Are independent correlates of major depression different between individuals with common chronic medical conditions and individuals without common chronic medical conditions?

It was hypothesized that the prevalence and odds of major depression would be significantly higher in individuals with chronic medical disorders and that major depression would be independently associated with increased health utilization, lost productivity and functional disability beyond those arising from having a chronic medical disorder.