We appreciate the thoughtful comments of Drs Weissman and Wickramaratne on our recently published article.1 The number of onsets for major depression (MD) in our sample falling into each decade were: younger than 10 years, 75; ages 10 to 19 years, 452; ages 20 to 29 years, 613; ages 30 to 39 years, 421; ages 40 to 49 years, 171; and ages 50 to 59 years, 22. In our sample, 11% of affected individuals (n=193) reported an age at onset (AAO) of after 40 years. Thoughts of death had a modest negative correlation with AAO (−0.10) and a stronger relationship with long duration (0.20) and impairment (0.12). We analyzed AAO as a continuous measure, with decade as a unit for ease of interpretation. Therefore, the hazard rate of 0.85 means that the baseline hazard rate was reduced (multiplied) by a factor of 0.85 for every 10-year increase in AAO. We thought this was easier to interpret than the 1-year change in hazard rate.
Kendler KS, Gardner CO, Prescott CA. Age of Onset and Familial Risk in Major Depression. Arch Gen Psychiatry. 2000;57(5):511. doi: