Table 8

Multiple regression analysis showing how the three domains of the Revised Fibromyalgia Impact Questionnaire predict subscales of the 36-Item Short Form Health Survey

SF-36 subscales (dependent variable)

R and R² predicted by combined FIQR domains

FIQR function

FIQR overall impact

FIQR symptoms

Physical functioning

R = 0.80^a

β = -0.803^a

β = -0.005

β = 0.015

R² = 0.62

pr = -0.641^a

pr = -0.004

pr = 0.014

Role limitation due to physical health

R = 0.55^a

β = -0.270^b

β = -0.261^c

β = -0.058

R² = 0.29

pr = -0.200^b

pr = -0.167^c

pr = -0.040

Role limitation due to emotional health

R = 0.45^a

β = 0.170

β = -0.234^c

β = -0.362^d

R² = 0.19

pr = 0.120

pr = -0.140^c

pr = -0.237^d

Energy/Fatigue

R = 0.55^a

β = 0.029

β = -0.133

β = -0.465^a

R² = 0.30

pr = 0.022

pr = -0.080

pr = -0.312^a

Emotional well-being

R = 0.58^a

β = 0.308^d

β = -0.210^c

β = -0.593^a

R² = 0.32

pr = 0.231^d

pr = -0.137^c

pr = -0.392^a

Social functioning

R = 0.57^a

β = 0.066

β = -0.287^b

β = -0.369^d

R² = 0.32

pr = 0.050

pr = -0.186^b

pr = -0.256^d

Pain

R = 0.70^a

β = -0.175^c

β = -0.219^c

β = -0.362^a

R² = 0.48

pr = -0.0152^c

pr = -0.163^c

pr = -0.285^a

General health

R = 0.57^a

β = -0.185^c

β = -0.085

β = -0.347^d

R² = 0.31

pr = -0.140^c

pr = -0.056

pr = -0.241^d

^aP < 0.0001; ^bP < 0.01; ^cP < 0.05; ^dP < 0.001. First column: adjusted R-square (R²) × 100 indicates the total variance in 36-Item Short Form Health Survey (SF-36) subscale accounted for by the common and unique variance in Revised Fibromyalgia Impact Questionnaire (FIQR) function, overall, and symptom domains taken together. Multiple regression (R) indicates the size of correlation between three FIQR domains as predictors taken together with the SF-36 subscale as criterion. Columns 2, 3, and 4 present the standardized regression (β) coefficients, which represent the unique contribution of the predictor variable, and the partial correlation (pr) coefficients, which represent the correlation for the one (FIQR) domain with the SF-36 subscale after controlling for the other two (FIQR) domains.

Bennett et al. Arthritis Research & Therapy 2009 11:R120   doi:10.1186/ar2783