Physical Therapy and Hospitalization among Medicare Beneficiaries with Low Back Pain: A Retrospective Cohort Study

Hendrik D. de Heer, Meghan Warren

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


STUDY DESIGN.: Retrospective cohort study. OBJECTIVE.: To evaluate associations between receipt and quantity of outpatient Physical Therapy (PT) during an episode of care and 30-day and 180-day hospital admissions for any condition and lumbar spine conditions. SUMMARY OF BACKGROUND DATA.: Low back pain (LBP) is a common cause of hospitalization and the most common reason Medicare beneficiaries utilize outpatient PT. The association between PT and hospitalization among patients with LBP is unknown. METHODS.: A national sample of Medicare Fee-for-Service claims included 413,608 beneficiaries with an ICD-9 code of LBP and 1,415,037 episodes of care between June 1 2010 and June 30 2011. Episodes were classified as PT episodes or non-PT episodes. Relative risk of hospitalization from the episode start date was calculated, adjusting for health status (Charlson co-morbidity index), an indicator of LBP severity (number of LBP ICD-9 codes) and demographics (sex, ethnicity, age). RESULTS.: The proportion of 30-day hospitalization for any condition was 3.42% for PT episodes of care, and 6.54% for non-PT episodes. For 180-day hospitalization, proportions were 15.45% (PT) and 21.65% (non-PT). The adjusted relative risk reduction of PT (vs. non-PT) was 41% for 30-days (99% CI 38%, 44%) and 22% for 180-days (20%, 24%). For admitting diagnoses of lumbar spine, reductions were 65% at 30-days and 32% at 180-days. More PT treatment days showed greater 30-day risk reductions. For any condition, compared to non-PT, reductions were 24% for 1-2 treatment days (lowest tertile), 45% for 3–7 days, and 65% for 8+ days (highest tertile). Stronger effects were found for lumbar spine admissions. Associations between PT quantity and 180-day hospitalization were less consistent. Limitations of Medicare claims include the potential for inaccuracies, limited knowledge about disease severity and which PT interventions were conducted. CONCLUSIONS.: Receipt of PT during an episode had a 22%-65% reduced relative risk of hospitalization, with greater short-term reductions for more PT treatment days.Level of Evidence: 3

Original languageEnglish (US)
StateAccepted/In press - Mar 18 2016

ASJC Scopus subject areas

  • Clinical Neurology
  • Orthopedics and Sports Medicine


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