title: Interpretation and power of a pooled index.
abstract: OBJECTIVE
  To describe, illustrate, provide statistical rationale and give clinical examples of the concept of a pooled index.
  
  
  METHODS
  No explicit design. Randomized control trials of patients diagnosed with rheumatoid arthritis from Rheumatic disease clinics, tertiary care hospitals and communities are used as examples to illustrate the pooled index technique. Interventions in rheumatic disease unit inpatient and outpatient care, occupational therapy and physiotherapy provided by Arthritis Society Therapists in the community were compared. Variables included active joint count, morning stiffness in min, mean of right and left grip strength in mm Hg, erythrocyte sedimentation rate in mm/h, a functional change score, and a pooled index.
  
  
  RESULTS
  The pooled index in each study detected a clinically important effect while individual measures were generally not able to declare the effect statistically significant.
  
  
  CONCLUSIONS
  The pooled index is a more powerful clinical outcome than any individual measure provided it is computed from at least 2 relevant clinical outcome measures that have low correlation with each other.
authors: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors: C H
authors: CH
authors: Goldsmith
authors: H A
authors: HA
authors: Smythe
authors: A
authors: A
authors: Helewa
mesh_terms: D001172:Arthritis, Rheumatoid / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D001799:Blood Sedimentation; D002986:Clinical Trials as Topic; D006801:Humans; D007596:Joints / Q000473:pathology / Q000503:physiopathology; D009132:Muscles / Q000503:physiopathology; D010146:Pain; D016032:Randomized Controlled Trials as Topic; D012720:Severity of Illness Index; D013223:Statistics as Topic; D016896:Treatment Outcome