a1 Policy and Evaluation Group, Queensland Centre for Mental Health Research, QLD, Australia
a2 School of Population Health, The University of Queensland, QLD, Australia
a3 Departments of Psychiatry and Community Health Sciences, University of Calgary, AB, Canada
Background Few studies have examined spontaneous remission from major depression. This study investigated the proportion of prevalent cases of untreated major depression that will remit without treatment in a year, and whether remission rates vary by disorder severity.
Method Wait-list controlled trials and observational cohort studies published up to 2010 with data describing remission from untreated depression at ≤2-year follow-up were identified. Remission was defined as rescinded diagnoses or below threshold scores on standardized symptom measures. Nineteen studies were included in a regression model predicting the probability of 12-month remission from untreated depression, using logit transformed remission proportion as the dependent variable. Covariates included age, gender, study type and diagnostic measure.
Results Wait-listed compared to primary-care samples, studies with longer follow-up duration and older adult compared to adult samples were associated with lower probability of remission. Child and adolescent samples were associated with higher probability of remission. Based on adult samples recruited from primary-care settings, the model estimated that 23% of prevalent cases of untreated depression will remit within 3 months, 32% within 6 months and 53% within 12 months.
Conclusions It is undesirable to expect 100% treatment coverage for depression, given many will remit before access to services is feasible. Data were drawn from consenting wait-list and primary-care samples, which potentially over-represented mild-to-moderate cases of depression. Considering reported rates of spontaneous remission, a short untreated period seems defensible for this subpopulation, where judged appropriate by the clinician. Conclusions may not apply to individuals with more severe depression.
(Received May 03 2012)
(Revised June 27 2012)
(Accepted July 05 2012)
(Online publication August 10 2012)
c1 Address for correspondence: Professor H. A. Whiteford, The University of Queensland, School of Population Health, Queensland Centre for Mental Health Research, Locked Bag 500, Sumner Park BC, QLD 4074, Australia. (Email: firstname.lastname@example.org)