Gender and Remission of Mental Illness
Schimmele, Christoph M., Wu, Zheng, Penning, Margaret J., Canadian Journal of Public Health
Objectives: There is a well-established association between gender and the prevalence of mental illness. The objective of this study was to determine whether gender also influences the timing of remission from illness. The regression analysis undertaken considered remission in terms of all ICD-9 mental disorders (codes 290-314). This analysis compares males and females on average length of treatment for mental illness and examines whether any gender differences in remission are generalized or disorder specific.
Methods: The statistical analysis was based on longitudinal (1990-2001) administrative data on 5,118 females and 2,470 males. The target population represented all individuals with an ICD-9 diagnosis of mental illness who were treated through the Medical Services Plan in British Columbia. The regression analysis used the generalized estimating equations method to model differences in length of treatment.
Results: There was a non-significant bivariate relation between gender and the timing of remission from mental illness. However, the multivariate findings demonstrated that a significant gender effect on remission emerges after controls were introduced for demographic and socio-economic characteristics. In particular, the timing of remission was somewhat longer for females. This effect was generalized and not restricted to specific illnesses.
Conclusions: The emergence of a significant effect after considering demographic and socio-economic characteristics suggests that a social disadvantage within the male sample (more single males) was suppressing a small negative effect of female gender on the timing of remission. In other words, a social disadvantage among males concealed an unexplained female disadvantage in remission.
Key words: Gender; remission; mental health
La traduction du résumé se trouve à la fin de l'article. Can J Public Health 2009;100(5):353-56.
Gender differences in the prevalence of mental illness are well documented,1-6 but whether gender also influences the timing of remission is unclear. Do the factors that contribute to a higher prevalence of illness among females also translate into a gender gap in the remission of illness? There is a good rationale to anticipate that gender is a factor in remission. For example, the literature suggests that gender dissimilarities in response to depression could lead to differences in the alleviation, complication or persistence of symptoms.7-13 In addition, gender differences in the clinical features of illness could also influence remission. Yet, the literature provides inconsistent conclusions and largely focuses on mood disorders.
One group of studies argues that gender has a non-significant effect on remission. For example, Benedetti et al.14 investigated whether gender influences the course of bipolar disorder. Their research showed that gender is non-significant in terms of the reduction of symptoms and number of recurrences of bipolar disorder. Benedetti et al. remarked that the effect of gender observed in other studies could be a result of ignoring dissimilarities in medical treatment. However, gender does not moderate the effect of pharmacological treatment for depression, according to Grubbe Hildebrandt et al.15 Their research demonstrates that, given equivalent therapies, gender is a nonsignificant factor in the post-treatment outcomes of depression.
Other studies indicate that gender has a significant effect.7-13 Riise and Lund13 demonstrated that depressed females have a higher risk of depression at long-term follow-up. The authors observed that the risk of chronic depression among females increased after baseline level of illness had been adjusted for. Riise and Lund's findings could reflect a higher rate of relapse among females, not a lower remission rate, but they at least demonstrated that depression is a more persistent condition for females and that gender can influence long-term prognosis. …