RESEARCH - Predicting depression in RA: the signal importance of pain extent and fatigue and comorbidity

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Arthritis Rheum. 2009 Apr 29;61(5):667-673.

Predicting depression in rheumatoid arthritis: The signal importance

of pain extent and fatigue, and comorbidity.

Wolfe F, Michaud K.

University of Kansas School of Medicine and National Data Bank for

Rheumatic Diseases, Wichita, Kansas.

OBJECTIVE: To determine the incidence of self-reported depression

(SRD) in rheumatoid arthritis and to identify and rank clinically

useful predictors of depression.

METHODS: We assessed 22,131 patients for SRD between 1999 and 2008. We

collected demographic, clinical and treatment data, household income,

employment and work disability status, comorbidity, scales for

function, pain, global, and fatigue, the Regional Pain Scale (RPS),

the Symptom Intensity (SI) scale (a linear combination of the RPS and

the fatigue scales) and linear combinations of the Health Assessment

Questionnaire, pain and global severity. We used logistic regression

analyses with multivariable fractional polynomial predictors, and

Random Forest analysis to determine the importance of the predictors.

RESULTS: The cross-sectional prevalence of self-reported depression

was 15.2% (95% confidence interval [95% CI] 14.7-15.7%) and the

incidence rate was 5.5 (95% CI 5.3-5.7) per 100 patient years of

observation. The cumulative risk of SRD after 9 years was 38.3% (95%

CI 36.6-40.1%). Almost all variables were significant predictors in

logistic models. In Random Forest analyses, the SI scale, followed by

comorbidity, best predicted self-reported depression, and no other

variable or combination of variables improved prediction compared with

the SI scale.

CONCLUSION: Pain extent and fatigue (SI scale) are the dominant

predictors of SRD. These variables, also of central importance in the

symptomatology of fibromyalgia, are powerful markers of distress. A

strong case can be made for the inclusion of these assessments in

routine rheumatology practice. In addition, actual knowledge of

comorbidity provides important insights into the patient's global

health and associated perceptions.

PMID: 19404997

http://www.ncbi.nlm.nih.gov/pubmed/19404997

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