Probable need for psychiatric treatment is not the same as depression

Nancy Frasure-Smith*, François Lespérance, Robert M Carney and Kenneth E Freedland

Department of Psychiatry, McGill University, Montreal, Que., Canada
Department of Psychiatry, University of Montreal, Montreal, Que., Canada
Director, Behavioral Medicine Center, Washington University School of Medicine, St. Louis, MI, USA
Department of Psychiatry, Washington University School of Medicine, St. Louis, MI, USA

* Corresponding author. Present address: Montreal Heart Institute, Research Centre, 5000 Belanger, Montreal, Que. H1T 1C8, Canada. Tel.: +1-514-376-3330x3024; Fax: +1-514-376-0979
E-mail address: nancy.frasure-smith{at}mcgill.ca

The title of the article by Stewart et al.1, in the November 2003 issue, implies that depression was assessed. However, the authors used the 30-item General Health Questionnaire with a cut-point >=5 to identify those with "depressive symptoms," who are elsewhere in the manuscript referred to as the "depressed". The GHQ is intended to screen primary care patients for probable need for psychiatric treatment.2 It is non-specific indicator of a variety of anxiety and mood disorders. It is not a measure of depressive symptoms or depression. Second, previous publications by the authors used a cut-point of 10 on this same measure to identify "GHQ cases of depression".3 This mixing of terminology and shifting of cut-points is troubling. There are similar problems with the literature review. Table 5 represents "cohort studies published before March 2003 that reported at least 30 fatal events." While the number of events is important for covariate control, the measures used and the timing of their administration are as important. Four of the studies listed did not use recognized measures of depression (Stewart et al1 and Jenkinson et al., 1993, Carinci et al., 1997 and Denollet et al., 1996). One assessed patients up to three years before an MI (Berkman et al., 1992), one assessed cardiac rehabilitation patients (Denollet et al., 1996), and one assessed patients taking amiodarone (Irvine et al., 1991). Three studies adjusted for covariates that are highly related to depression (Type-D personality (Denollet et al., 1996), social support and fatigue (Irvine et al., 1999), and perceived global health (Stewart et al.1)) and thus not true confounders.4 By doing so these studies explained away depression's impact on outcomes. In this context, the statement that "in eight of the 10 studies listed, there was no statistically significant association between depression and mortality after adjustment for potential confounders" is misleading.

This article presents a secondary analysis of a randomized trial of an agent that had a significant long-term impact on cardiovascular morbidity and mortality. However, no mention is made of treatment group. Because of potential interactions between pravastatin and baseline factors in predicting cardiovascular outcomes, it is inappropriate to analyze these data without considering the role of treatment group. More specifically, we recently observed a significant interaction between statin use and major depression in C-reactive protein (CRP) levels.5 While depression was linked to increased CRP in stable cardiac patients not taking statins, the relationship did not exist in the presence of statins. This suggests that links between psychological factors and cardiovascular outcomes may be moderated by lipid lowering medications. If this is the case, the current overall results, showing no significant link between GHQ scores and cardiac events, may mask an important relationship in the patients on placebo.

In summary, improved understanding of the relationship between depression and outcomes in cardiac patients depends on objective and accurate reporting of both positive and negative studies. Unfortunately, the article by Stewart et al., failed to present a balanced view of the literature and did not provide informative findings.

References

  1. Stewart RAH, North FM, West TM et al. Depression and cardiovascular morbidity and mortality: cause or consequence? Eur. Heart J. 2003;24:2027–2037.[Abstract/Free Full Text]
  2. Goldberg DP. The Detection of Psychiatric Illness by Questionnaire. London: Oxford University Press; 1972. .
  3. Stewart RA, Sharples KJ, North FM et al. Long-term assessment of psychological well-being in a randomized placebo-controlled trial of cholesterol reduction with Pravastatin. Arch. Intern. Med. 2000;160:3144–3152.[Abstract/Free Full Text]
  4. Mendes de Leon C. Depression and social support in recovery from myocardial infarction: confounding and confusion. Psychosom Med. 2000;61(738):739.
  5. Lespérance F, Frasure-Smith N, Irwin M, Théroux P. The association between major depression, sICAM-1, interleukin-6, and CRP in patients with recent acute coronary syndromes. A. J. Psychiatry. 2004;161:271–277.[Abstract/Free Full Text]




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