Weighted index explained more variance in physical function than an additively scored functional comorbidity scale

J Clin Epidemiol. 2011 Mar;64(3):320-30. doi: 10.1016/j.jclinepi.2010.02.019. Epub 2010 Aug 16.


Objective: 1) examine association between the Functional Comorbidity Index (FCI) and discharge functional status (FS); 2) examine impact of FCI on FS when added to comprehensive models; and 3) compare additive FCI with weighted FCI and list of condition variables (list).

Study design and setting: Patients were drawn from Focus On Therapeutic Outcomes, Inc. (FOTO) database (1/1/06-12/31/07). FS collected using computer adaptive tests. Linear regression examined association between FCI and FS. Three methods of including functional comorbidities (FC) were compared.

Results: Relationship between FCI and FS varied by group (range, 0.02-0.9). Models with weighted index or list had similar R². Weighted FCI or list increased R² of crude models by <0.01 for cervical, shoulder, and lumbar; by 0.01 for wrist/hand, knee, and foot/ankle; by 0.02 for hip; by 0.03 for elbow; and by 0.08 for neurological. Addition of FCI to comprehensive models added <0.01 to R² (all groups). Weighted FCI increased R² by <0.01 for cervical, lumbar, and shoulder; by 0.01 for wrist/hand, hip, knee, and foot/ankle; by 0.02 for elbow; and by 0.04 for neurological; whereas list increased R² by <0.01 for cervical, shoulder, and lumbar; by 0.01 for knee and foot/ankle; by 0.02 for elbow, wrist/hand, and hip; and by 0.05 for neurological.

Conclusion: List of comorbidities or weighted FCI is preferable to using additive FCI.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Ambulatory Care
  • Comorbidity
  • Epidemiologic Methods
  • Female
  • Humans
  • Male
  • Middle Aged
  • Musculoskeletal Diseases / epidemiology
  • Musculoskeletal Diseases / rehabilitation*
  • Outcome Assessment, Health Care*
  • Patient Discharge
  • Physical Therapy Modalities*
  • Recovery of Function*
  • Treatment Outcome