Commentary: Explaining enormous variations in rates of disorder in trauma-focused psychiatric epidemiology after major emergencies

Abstract

There has been a surge of interest in the last 20 years in the mental health effects of conflict and other major disasters in lowand middle-income countries (LAMIC). In particular, post-traumatic stress disorder (PTSD) and major depression have received substantial attention. It has become evident that there are large, unexplained variations in prevalence rates identified through trauma-focused psychiatric epidemiology in such settings. For example, Mollica et al.’s classic study found prevalence rates of PTSD of 15% among genocide-exposed Cambodians, while Neugebauer et al.’s sophisticated report in this issue of the Journal identifies rates of 53–62% of PTSD in genocide-exposed Rwandans. The wide variation in the prevalence rates in studies of PTSD and depression may be attributable to differences in context, methodology or both. Discussion sections of reports often highlight only a few factors that could explain the size of obtained rates. Although peer review helps shape discussion sections, authors usually have enormous discretion in deciding what factors to report. Readers are left with the challenge of tracking all reported and unreported methodological and contextual factors that could explain a study’s results. We have developed a scheme that may help to systematically identify factors influencing the size of observed prevalence rates of disorders in populations affected by major emergencies in LAMIC. The scheme may prove useful for readers and journal peer reviewers alike. The scheme, which we will apply below to Neugebauer et al.’s study, was built as follows. We searched the following medical, psychiatry and speciality journal websites: American Journal of Psychiatry; Archives of General Psychiatry; British Journal of Psychiatry; British Medical Journal; Culture Medicine and Psychiatry; JAMA, Journal of Traumatic Stress, Lancet, Psychological Medicine; Social Science and Medicine; and Transcultural Psychiatry for studies published after 1998 with data collected on depression or PTSD among civilians after major emergencies in LAMIC (references available upon request). Of 43 studies, 11 (26%) pertained to major natural disasters and 32 (74%) pertained to major human-made disasters (e.g. war). All articles were original contributions, and 40 (93%) made comments explaining the magnitude of findings in the articles’ discussion sections. In addition, we reviewed editorials, commentaries and letters to the editor linked to the identified articles. We thematically analysed discussion sections of all papers. We categorized authors’ explanations for observed rates as (i) either methodological or contextual in nature and (ii) explaining either relatively higher or lower observed rates. In addition, we categorized some explanations as (iii) reflecting general methodological limitations causing uncertainty in the validity of the study, with unknown impact on the magnitude of observed rates. Table 1 provides an overview of the explanations for relatively high or low rates ascribed in these studies. We studied the research reported in this issue of the Journal and rated different methodological and contextual factors in the study from 1 (not a factor in explaining size of obtained rate) to 5 (definitive factor in explaining size of obtained rate) (see bracketed numbers in Table 1). If no information was available in the paper on an element, then we rated it 3. Starting with the cell in the bottom left, we will discuss here ratings of 4 and 5, which are of main interest in explaining findings. The study took place in 1995 in a context (recent genocide that was preceded and followed by violence, fears of revenge killings, ongoing mass displacements, risk of cholera outbreaks, etc.) that not only involved mass loss and trauma but also a highly stressful recovery * Corresponding author. Department of Mental Health and Substance Abuse, World Health Organization, Geneva, Switzerland. E-mail: vanommerenm@who.int 1 Faculty of Medicine, University of Toronto, Toronto, Canada. 2 Department of Mental Health and Substance Abuse, World Health Organization, Geneva, Switzerland. Published by Oxford University Press on behalf of the International Epidemiological Association