Association of Self-Reported Improvement After 4 Weeks and Outcomes After 52 Weeks Among Adolescents With Patellofemoral Pain and Osgood-Schlatter Disease.

BACKGROUND

Short-term, self-reported changes in symptom severity for musculoskeletal pain disorders may be more strongly associated with long-term prognoses than baseline patient characteristics, because such changes describe a trajectory and not a state.

PURPOSE

To investigate whether short-term improvement in self-reported symptom severity is associated with long-term recovery among adolescents with nontraumatic knee pain (patellofemoral pain [PFP] or Osgood-Schlatter disease [OSD]).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The authors evaluated data from 2 prospective clinical trials that included adolescents aged 10 to 14 years with either PFP (n = 151) or OSD (n = 51). Both groups underwent a self-management rehabilitation program including activity modification, education, and exercise. The primary outcome was a 7-point global rating of change (GROC) scale (from "much improved" to "much worse"); participants were considered to have improved symptoms if they reported being "much improved" or "improved." Outcomes were collected after 4 and 52 weeks. To investigate whether participants who improved according to GROC scores after 4 weeks were more likely to improve after 52 weeks compared with those who had not improved after 4 weeks, the authors calculated the relative risk (RR) of being improved.

RESULTS

Among participants with PFP, reporting an improvement after 4 weeks increased the likelihood of an improvement after 52 weeks (RR = 1.26; 95% CI, 1.06-1.50; = .008); among those with OSD, reporting an improvement after 4 weeks did not increase the likelihood of an improvement after 52 weeks (RR = 1.06; 95% CI, 0.88-1.28; = .545). Among participants with PFP who did not improve after 4 weeks, 73% reported improvement after 52 weeks, whereas among participants with OSD who did not improve after 4 weeks, 89% reported improvement after 52 weeks.

CONCLUSION

Self-reported improvement after 4 weeks of treatment was associated with better outcomes after 52 weeks among adolescents with PFP. This association was present only among adolescents with PFP, as almost all adolescents with OSD improved after 52 weeks, regardless of short-term results. Importantly, even among adolescents reporting no improvement after 4 weeks, a large proportion reported improvement after 52 weeks. This highlights the importance of following the rehabilitation program regardless of the short-term response.