Table 4.

Poisson rates for major depression and minor depression

	No. of depression events	Depression years in time period	Events per year	P valuea
Comparison A
Major depression
3 yr
Before POI	30	134.5	0.22	0.19
After POI	17	50.9	0.33
5 yr
Before POI	39	197.0	0.20	0.19
After POI	21	72.3	0.29
10 yr
Before POI	54	289.9	0.19	0.16
After POI	27	101.5	0.27
Minor depression
3 yr
Before POI	4	31.4	0.13	0.18
After POI	6	17.1	0.35
5 yr
Before POI	9	44.8	0.20	0.19
After POI	8	20.3	0.40
10 yr
Before POI	11	61.8	0.18	0.04
After POI	9	20.5	0.44
Comparison B
Major depression
3 yr
Before MCI	7	58.4	0.12	0.16
After MCI	33	144.6	0.22
5 yr
Before MCI	10	87.6	0.11	0.13
After MCI	41	204.6	0.20
10 yr
Before MCI	19	128.3	0.15	0.27
After MCI	58	290.0	0.20
Minor depression
3 yr
Before MCI	2	14.7	0.14	0.74
After MCI	8	36.2	0.22
5 yr
Before MCI	4	21.0	0.19	1.0
After MCI	10	49.3	0.20
10 yr
Before MCI	5	30.0	0.17	0.81
After MCI	14	66.3	0.21

Comparison A: Comparisons were performed as follows: 1) Poisson rates of depression were calculated (i.e. number of women with depression per person-years in the time period) to compare the number of the depressions that occurred in women before and after the diagnosis of POI. Three sets of Poisson rates were calculated for major as well as for minor depressions that were limited to depressions occurring within 3-, 5-, and 10-yr windows surrounding the diagnosis of POI. In these calculations, women whose depressions did not occur during the windows of time before or after the diagnosis of POI (i.e. 3, 5, and 10 yr, respectively) contributed person-years to the denominator. For each set, the before and after rates were compared using an exact Poisson test of homogeneity. 2) Kaplan-Meier survival analyses were performed to compare the onset of depressive episodes in the absolute number of days occurring before and after the diagnosis of POI. Neither the Poisson rates for 3-, 5-, and 10-yr intervals (with one exception) nor the Kaplan-Meier analyses demonstrated a significant difference between the number of depressive episodes before and after the diagnosis of POI (for either major or minor depressions) [Kaplan-Meier: major depression, hazard ratio (after:before) = 1.5; P = 0.09; minor depression, hazard ratio (after:before) = 2.6; P = 0.054].

Comparison B: Poisson rates and Kaplan-Meier survival analyses also were calculated to compare the number of episodes of depression that occurred before and after the reported onset of MCI. Neither the comparisons of the three sets of Poisson rates nor the Kaplan-Meier survival analyses identified significant differences in the number of depressive episodes (major or minor) preceding compared with those occurring after the onset of MCI [Kaplan-Meier: major depression, hazard ratio (after:before) = 1.2; P = 0.4; minor depression, hazard ratio (after:before) = 1.2; P = 0.7].

^aExact Poisson test of homogeneity.