Table 4.

Age- and Sex-Adjusted Longitudinal Associations of Individual Physical, Cognitive, and Mental Health Status Variables at 6 Months With Fatigue Symptoms at 12-Month Follow-up (N = 732)

Variable at 6 Months Follow-up [Scaled by 0.5 SD]	Mean Difference (95% CI) in Fatigue at 12 Monthsa [Positive Value = Less Fatigue]	P
Physical Component summary (SF-36v2) [∼6 points]b	1.0 (0.3 to 1.5)	.002
Physical Functioning (FPI –SF) [∼0.5 point]	1.2 (0.6 to 1.7)	< .001
Cognition (MMSE) [∼1 point]	0.6 (0.2 to 1.1)	.006
Mental Component summary (SF-36v2) [∼7 points]	1.0 (0.4 to 1.6)	< .001
PSTD symptoms (IES-R) [∼0.5 points]	–1.1 (–1.6 to –0.5)	< .001
Anxiety symptoms (HADS-Anxiety Subscale) [∼2.5 points]	–1.0 (–1.6 to –0.4)	< .001
Depression symptoms (HADS-Depression Subscale) [2.5 points]	–1.7 (–2.3 to –1.0)	< .001

For SF-36, FPI-SF and MMSE higher scores = better function; for IES-R and HADS higher scores = greater symptoms. See Table 1 legend for expansion of abbreviations.

^aEach row reports the results of a separate regression model that evaluates the age- and sex-adjusted association of the variable named in the row at 6 months, with fatigue symptoms at 12 months. Analyses were conducted by using a longitudinal random effects regression model. Fatigue symptoms were measured by using the transformed score from the validated Functional Assessment of Chronic Illness Therapy-Fatigue Scale (range: 0 to 100), with higher scores representing less fatigue (range, 0-100). Values presented represent the estimated mean difference in 12-month fatigue score for a 0.5 SD difference in the variable named in the row at 6 months.

^bThe interpretation of first row is as follows: “If Patient A had a Physical Component Summary score that was 0.5 standard deviations higher than Patient B at 6 month follow-up, then Patient A’s expected fatigue score would be 1.0 point higher than Patient B’s at 12 month follow-up.”