Short Form 36 (SF-36)

Reference: Angst et al. 2001. “Smallest detectable and minimal clinically important differences of rehabilitation intervention with their implications for required sample sizes using WOMAC and SF-36 quality of life measurement instruments in patients with osteoarthritis of the lower extremities” Arthritis Care & Research, 45(4),  384–391. SEM & MDC: SF-36 score SEM and MDC (calculated from data in Lin et al. 2007):

• There is published data and norms available for some health conditions as well as for the general population (Canada and United States).
• Higher scores indicate higher levels of health.
• Further research is needed on using the SF-36 for individuals with SCI to understand how they are answering the questions to ensure the data is valid.
• Normative data for the SCI population have not been reported at this time
• Published data on the SCI population is available for comparison (see Interpretability section of the Study Details sheet).

Reliability

• Internal consistency ranges from moderate to high for total SF-36 (Cronbach’s a = 0.82) and subscales:
  • Physical Functioning (Cronbach’s a = 0.91-0.98)
  • Role Physical (Cronbach’s a = 0.94)
  • Bodily Pain (Cronbach’s a = 0.79)
  • General Health (Cronbach’s a = 0.79-0.82)
  • Vitality (Cronbach’s a = 0.76)
  • Social Functioning (Cronbach’s a = 0.72)
  • Role Emotional (Cronbach’s a = 0.89)
  • Mental Health (Cronbach’s a=0.78)
• Inter-rater and intra-rater reliability ranges from moderate to high for the SF-36 subscales: (Inter-rater ICC, intra-rater ICC)
  • Physical Functioning (0.67, 0.71)
  • Role Physical (0.90, 0.89)
  • Bodily Pain (0.70, 0.87)
  • General Health (0.41, 0.87)
  • Vitality (0.86, 0.93)
  • Social Functioning (0.52, 0.93)
  • Role Emotional (0.98, 0.99)
  • Mental Health (0.57, 0.77)

(Forchheimer et al. 2004, King & Roberts 2002, Lin 2007, Luther et al. 2006, Van Leeuwen et al. 2012)

Validity

• Correlation of the SF-36 mental summary is high with Behavioural Risk Factor Surveillance System items (Pearson’s r=-0.650 to -0.761), low with the Quality of WellBeing (Pearson’s r=0.116), and low with the Instrumental Activities of Daily Living (Pearson’s r=0.262).
• Correlation of the SF-36 physical summary is moderate with the Behavioural Risk Factor Surveillance System items (Pearson’s r=-0.458 to -0.489), the Quality of WellBeing (Pearson’s r=0.417) and the Instrumental Activities of Daily Living (Pearson’s r=-0.357)
• The ability of the SF-36 to discriminate among subgroups with respect to age, education, marital status, employment, time since injury, level of injury, and self-care ability was tested using the Mann-Whitney U-test.
• The domains of the SF-36 had significant discriminant validity between employment and self-care ability; the discriminant ability differed with other characteristics. Overall, the SF-36 domains significantly discriminated between subgroups in terms of 2-4 characteristics.

(Forchheimer et al. 2004, King & Roberts 2002, Lin 2007, Luther et al. 2006, Van Leeuwen et al. 2012, Andresen et al. 1999, Bonne-Lee et al. 2008, Miller et al. 2008, Raichle et al. 2006, Anton et al. 2006, Horner-Johnson et al. 2010)

Responsiveness

• Significantly lower scores for individuals with SCI than the nondisabled group were reported on the Physical Functioning, Bodily Pain and Role-Physical domains.
• However, all Vitality subscale items showed significant positive differential functioning for people with SCI when controlling for total physical health scores.

(Lin 2007, Bonne-Lee et al. 2008, Horner-Johnson et al. 2010)

Floor/Ceiling Effect

• Floor effects and ceiling effects reported for the SF-36.
• 3 subscales (role physical, social functioning, role emotion) exhibited ceiling effects between 22.5 and 75.3%.
• 2 subscales (physical functioning and role physical) exhibited floor effects 24.2% and 36.3%, respectively.

(King & Roberts 2002, Van Leeuwen et al. 2012, Andresen et al. 1999, Lin 2007, Bonne-Lee et al. 2008)

Reviewer

Dr. Ben Mortenson, Brodie Sakakibara, John Zhu, Jeremy Mak, Risa Fox

Date Last Updated

24 July 2020