Arch Gen Psychiatry -- Life Event Dimensions of Loss, Humiliation, Entrapment, and Danger in the Prediction of Onsets of Major Depression and Generalized Anxiety, A…
1/27/07 10:12 AM
different lengths and that the results can be interpreted similarly to a Cox proportional hazards model. Each person-month of observation contained information as to which, if any, SLEs occurred or when an episode of MD or GAS began. Each observation record also included 3 covariates: sex, previous history of MD or GAS within the past year, and the hazard rate (HR) for MD or GAS for that month. When a twin
experienced an episode of MD or GAS, the data were censored until the twin was again at risk, having recovered from that episode.
Our person-month files with high-threat SLEs present 2 sources of clustering: multiple observations per person and per twin pair. To handle this complex covariance structure, we used the method of
independence estimating equations,
which are generalized estimating equations with a diagonal working
matrix. This method gives consistent estimators of standard errors even when the working
correlation structure is incorrect. Although our hypotheses were directional, 2-tailed P values are reported.
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PURE MD • Top • Introduction • Methods • Results • Comment • Author information • References For all of the analyses, the sample contained 7322 twins with 98 592 person- months. Of these person-months, 4251 (4.3%) contained a high-threat event. The polycoric correlations of ratings of the 4 SLE dimensions on these 4251 events were low between humiliation and entrapment, humiliation and danger, and loss and danger ( 0.10 for all) but higher between entrapment and danger (0.48), humiliation and loss (0.39), and entrapment and loss (0.32). The mean (SD) ratings for
these 4 dimensions were as follows: loss, 2.74 (0.67); humiliation, 0.61 (1.19); entrapment, 0.25 (0.81); and danger, 1.55 (1.38).
The baseline risk per month for a pure MD episode was 0.6%. In the month of occurrence, high-threat events were strongly associated with pure depressive onsets (HR, 10.1; 95% CI, 7.2-14.0; P<.001). Table 2 depicts the impact of event dimensions, in the month of occurrence, on the HRs for pure MD. In months containing high-threat events, the risk for a depressive onset was significantly increased by high ratings for loss (HR, 1.70) and humiliation (HR, 1.44) but not for entrapment (HR, 1.02) or danger (HR, 0.95). We then ran a model containing the 2 strong predictors, and both remained significant (loss: HR, 1.56; 95% CI, 1.34-1.81; and humiliation: HR, 1.29; 95% CI, 1.14-1.46; P<.001 for both), indicating that each dimension independently contributed to predicting depressive onsets.
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Table 2. Hazard Ratios (95% CIs) for Onset of 3 Disorders by Month After Occurrence of High-Threat Events
Next, we examined the impact of event dimensions on risk of a pure depressive onset 1, 2, and 3 months after the event occurrence. None were significant (Table 2).
MIXED DEPRESSION/ANXIETY EPISODES
The baseline risk per month for a mixed depression/anxiety episode was 0.5%. In the month of occurrence, high-threat events were strongly associated with the onset of a mixed depression/anxiety episode (HR, 6.6; 95% CI, 5.3-8.3; P<.001). In months containing high-threat events, the risk for an onset of mixed episodes was significantly increased by high ratings for loss (HR,
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