Synchrony of change in depressive symptoms, health status, and quality of life in persons with clinical depression

Table 5 Appendix Table 1: Standard Deviation of Change from Baseline (original scale)

	Screener to Baseline *	Baseline to 6 weeks	Baseline to 3 months	Baseline to 9 months
CESD	8.75	10.48	11.65	13.67
MCS	9.49	10.83	11.77	13.06
MHI5	17.18	19.08	20.55	23.45
Do Less:Emotional	0.47	0.50	0.54	0.56
PCS	7.74	8.02	8.77	9.69
Do Less:Physical	0.50	0.52	0.53	0.55
EVGGFP	0.68	0.67	0.73	0.81
QLDS		6.11	6.41	7.40
QOL:Rate		0.81	0.83	0.91
WQ:Environment		1.78	2.00	2.15
WQ:Physical		2.25	2.55	2.86
WQ:Psychological		2.17	2.42	2.78
WQ:Social Relationships		2.92	3.16	3.38

* The standard deviation of the difference between the screening value and the baseline value 14 days later is for persons whose screening value was 16 or higher. The last 6 instruments were not used in the screening population.
The information in Appendix Table 1 should be useful to others in planning future studies of clinically depressed persons. For example, a study might be designed to affect the change in QOL over 3 months as measured by the QLDS. The 3-month change-score had standard deviation 6.41. To detect a difference of, say, 2 points between a treatment and control group with 80% power, the necessary sample size is (1.96+.84)² * 2 * 6.41² /2² = 161 persons per treatment group. The effect size or responsiveness of an instrument can be calculated from this information as well [29]. Finally the test-retest reliability of the instrument for a population with one CESD score above 16 and a positive CIDI assessment may be approximated from the screener-to-baseline information.

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