Most epidemiologic studies concerned with Major Depressive Disorder have employed cross-sectional study designs. Assessment of lifetime prevalence in such studies depends on recall of past depressive episodes. Such studies may underestimate lifetime prevalence because of incomplete recall of past episodes (recall bias). An opportunity to evaluate this issue arises with a prospective Canadian study called the National Population Health Survey (NPHS).
The NPHS is a longitudinal study that has followed a community sample representative of household residents since 1994. Follow-up interviews have been completed every two years and have incorporated the Composite International Diagnostic Interview short form for major depression. Data are currently available for seven such interview cycles spanning the time frame 1994 to 2006. In this study, cumulative prevalence was calculated by determining the proportion of respondents who had one or more major depressive episodes during this follow-up interval.
The annual prevalence of MDD ranged between 4% and 5% of the population during each assessment, consistent with existing literature. However, 19.7% of the population had at least one major depressive episode during follow-up. This included 24.2% of women and 14.2% of men. These estimates are nearly twice as high as the lifetime prevalence of major depressive episodes reported by cross-sectional studies during same time interval.
In this study, prospectively observed cumulative prevalence over a relatively brief interval of time exceeded lifetime prevalence estimates by a considerable extent. This supports the idea that lifetime prevalence estimates are vulnerable to recall bias and that existing estimates are too low for this reason.
Conventional estimates of antidepressant (AD) utilization in major depressive syndrome (MDS) have been low, but this may be partially because ongoing AD use by individuals with resolved MDS is not included. Valid estimates of AD utilization should include this ongoing use for MDS, but this is difficult since most surveys do not collect data on the reason for taking ADs. Only a proportion (f(dep)) of the nondepressed (nMDS) population taking ADs does so for depression. Published studies have not reported this proportion, and data required to estimate f(dep) are not usually available from surveys. The current study was performed to (1) estimate f(dep) by employing information on past history of depression, and (2) use the estimate to obtain an "adjusted" AD utilization rate, including resolved MDS subjects taking ADs. Data were collected in Calgary in 1998 and 1999 by random-digit dial telephone interview from consenting adults aged 18+ years. MDS was assessed using the Composite International Diagnostic Interview Short Form for Major Depression (CIDI-SFMD). Data were gathered on current medications, past depression, and current chronic physical illness. Of 2,542 respondents, 17.1% had MDS as defined by the CIDI-SFMD. A total of 20.2% of MDS and 3.2% of nMDS subjects were taking ADs. Of nMDS individuals taking ADs, 70.6% reported past depression (f(dep) = 70.6%). An "adjusted" AD utilization rate including this group was 28.2%. Physical illnesses that can be treated with ADs affected only 30.0% of nMDS subjects without past depression taking ADs. This study suggests that most individuals without active depression taking ADs do so for depression. AD utilization rates that ignore this group may be unrealistically low. AD use among nMDS subjects without previous depression is probably not primarily for physical illnesses. Limitations include the use of a brief predictive instrument for MDS, and self-report of past depression.
Several studies have suggested that there may be an increased prevalence of affective disorders in people with motor neuron disease (MND). However, the literature is inconsistent, possibly because of small sample sizes in the existing studies. The Canadian province of Alberta has a universal health care system in which physician contacts are recorded along with ICD-9-CM diagnostic codes. In this analysis, diagnostic codes indicative of MND and affective disorders were used. Stratified analysis and logistic regression were used in the analysis. There were 336 cases of MND leading to a prevalence of 14.5 per 100,000 in provincial residents > or =20 years old. Affective disorders were identified in 8.6% of the total population during the same year. The crude odds ratio for affective disorders in MND was 2.3 (95% CI = 1.7-3.0). However, the prevalence of affective disorders declined with increasing illness duration.
The prevalence of major depression is increased in people with chronic medical conditions. The objective of this analysis was to determine whether this is due to a higher incidence, an impact on prognosis, or an effect of mortality.
An analysis of data collected in two national Canadian general health surveys was carried out. Markov models representing period prevalence, incidence, mortality, and recovery were developed using these data sources. Monte Carlo simulation, using tracking variables, was used to evaluate the model.
The incidence of major depression was higher in subjects with chronic medical conditions. However, the pattern of recovery was also different: Subjects with chronic medical conditions had slightly longer episode durations. The analysis of mortality data was limited by a small number of deaths in the survey sample; however, the models suggested that the impact of mortality on the association is small.
An elevated prevalence of major depression has been observed in persons with chronic medical conditions. Two factors seem to contribute to this association: increased episode incidence and duration.
The Canadian Community Health Survey (CCHS) is a cross-sectional survey that has collected information on health determinants, health status and the utilization of the health system in Canada since 2001. Several hundred articles have been written utilizing the CCHS dataset. Previous analyses of statistical methods utilized in the literature have focused on a particular journal or set of journals to understand the statistical literacy required for understanding the published research. In this study, we describe the statistical methods referenced in the published literature utilizing the CCHS dataset(s).
A descriptive study was undertaken of references published in Medline, Embase, Web of Knowledge and Scopus associated with the CCHS. These references were imported into a Java application utilizing the searchable Apache Lucene text database and screened based upon pre-defined inclusion and exclusion criteria. Full-text PDF articles that met the inclusion criteria were then used for the identification of descriptive, elementary and regression statistical methods referenced in these articles. The identification of statistical methods occurred through an automated search of key words on the full-text articles utilizing the Java application.
We identified 4811 references from the 4 bibliographical databases for possible inclusion. After exclusions, 663 references were used for the analysis. Descriptive statistics such as means or proportions were presented in a majority of the articles (97.7%). Elementary-level statistics such as t-tests were less frequently referenced (29.7%) than descriptive statistics. Regression methods were frequently referenced in the articles: 79.8% of articles contained reference to regression in general with logistic regression appearing most frequently in 67.1% of the articles.
Our study shows a diverse set of analysis methods being referenced in the CCHS literature, however, the literature heavily relies on only a subset of all possible statistical tools. This information can be used in identifying gaps in statistical methods that could be applied to future analysis of public health surveys, insight into training and educational programs, and also identifies the level of statistical literacy needed to understand the published literature.
Cites: Health Place. 2011 Jan;17(1):195-20621075033
Antidepressant utilization can be used as an indicator of appropriate treatment for major depression. The objective of this study was to characterize antidepressant utilization in Canada, including the relationships of antidepressant use with sociodemographic variables, past-year and lifetime depression, number of past depressive episodes, and other possible indications for antidepressants.
We examined data from the Canadian Community Health Survey (CCHS) Cycle 1.2. The CCHS was a nationally representative mental health survey (N=36,984) conducted in 2002 that included a diagnostic instrument for past-year and lifetime major depressive episodes and other psychiatric disorders and a record of past-year antidepressant use.
Overall, 5.8% of Canadians were taking antidepressants, higher than the annual prevalence of major depressive episode (4.8%) in the survey. Among persons with a past-year major depressive episode, the frequency of antidepressant use was 40.4%. After application of adjustments for probable successful outcomes of treatment, the estimated frequency of antidepressant use for major depression was more than 50%. Frequency of antidepressant treatment among those with a history of depression but without a past-year episode increased with the number of previous episodes. Among those taking antidepressants over the past year, only 33.1% had had a past-year episode of major depression. Migraine, fibromyalgia, anxiety disorder, or past depression was present in more than 60% of those taking antidepressants without a past-year episode of depression.
The CCHS results suggest that antidepressant use has increased substantially since the early 1990s, and also that these medications are employed extensively for indications other than depression.
Mental health is an emerging priority for health surveillance. It has not been determined that the existing data sources can adequately meet surveillance needs. The objective of this project was to explore the use of telephone surveys as a means of collecting supplementary surveillance information. A computer-assisted telephone interview was administered to 5,400 subjects in Alberta. The interview included a set of brief, validated measures for evaluating mental disorder prevalence and related variables. The individual subject response rate was 78 percent, but a substantial number of refusals occurred at the initial household contact. The age and sex distribution of the study sample differed from that of the provincial population prior to weighting. Prevalence proportions did not vary substantially across administrative health regions. There is a potential role for telephone data collection in mental health surveillance, but these results highlight some associated methodological challenges. They also draw into question the importance of regional variation in mental disorder prevalence--which might otherwise have been a key advantage of telephone survey methodologies.
Structured diagnostic inter- views include items that evaluate physical etiologies for mood and anxiety disorders. The objective of this article was to assess the impact of such items.
A mental health survey in Canada collected data from n = 36,984 household residents. The lifetime prevalence of mood and anxiety disorders was calculated with and without exclusions due to physical causes.
Approximately 10% of subjects with a lifetime depressive disorder reported that all of their episodes were due to one or more physical cause. Many of the reported etiologies were implausible given the DSM-IV requirement that the disturbance be a "direct physiological consequence" of the physical cause. The results were similar for manic episodes and anxiety disorders.
Structured diagnostic interviews assess physical etiologies in ways that are subject to inconsistency and inaccuracy. Physical etiology items may bias estimates by introducing etiological opinions into the assessment of disorder frequency.
Investigations of the effects of antidepressant treatment for individuals with major depression have focused on short-term outcomes in individuals that meet very specific criteria; however, there is limited knowledge about long-term outcomes associated with antidepressant use in general population samples. This study aimed to investigate the long-term outcomes associated with antidepressant use by focusing on 486 depressed adults in a prospective observational Canadian cohort in 1998/99. We used logistic regression to investigate the association between antidepressant use and depression status 8 years later. Non-random allocation to treatment was accounted for by a propensity-for-treatment model which included thirteen predictors of antidepressant use, including: severity of depressive symptoms, previous episodes of depression (from 1994 to 1997), physical health condition, social support and socio-demographic characteristics. 29% of individuals with major depression reported antidepressant use. After adjusting for propensity for treatment in 1998/99, and antidepressant use from 2000 to 2007, depressed individuals who reported antidepressant use in 1998/99 were less likely to be depressed in 2006/07 compared to those who did not report antidepressant use (OR = 0.36, 95% CI: 0.15-0.88). Amongst individuals with symptoms of major depression, those reporting use of anti-depressants at baseline exhibited improved long-term outcomes in comparison to those who did not report treatment.
This study examined associations between mood disorders, anxiety disorders, substance dependence or harmful alcohol use, and occupational status and disability in a general population sample.
Data from the Canadian Community Health Survey Cycle 1.2-Mental Health and Well-Being (CCHS-1.2), a representative cross-sectional survey, were analyzed. The total sample was narrowed to individuals between the ages of 18 and 64 years, the age range most likely to be working.
Of the 27,332 persons surveyed, 946 had a mood disorder only, 831 had an anxiety disorder only, 730 had substance dependence only, and 966 had more than one disorder. Twenty-three percent reported that during the previous week they were not at a job or were permanently unable to work (27% with mood disorder only, 30% with anxiety disorder only, and 20% with substance dependence only, and 34% with more than one disorder). In unadjusted analyses, mood and anxiety disorders were associated with absence from work during the week preceding the interview, whereas substance dependence was not. After adjustment for other variables using logistic regression, an association of substance dependence and work absence emerged. Each category of disorder was strongly associated with a greater likelihood of disability days or days spent in bed for mental health reasons.
On a population level, mood and anxiety disorders and substance dependence were associated both with not working during the week preceding the interview as well as an increase in reported disability or bed days. The strength of association appears to be stronger for mood and anxiety disorders.