Data and Sample

This study used private health insurance administrative data from 2009 to 2013 housed at the Health Care Cost Institute (HCCI). HCCI represents over 50 million individuals per year with over 1 billion insurance claims from four insurance companies: Humana, UnitedHealth Group, Blue Cross/Blue Shield, and Kaiser Permanente. From this sample, we extracted data for patients aged 18–64 years old residing in a convenience sample of northwestern United States (i.e., Alaska, Idaho, Montana, Oregon, Washington, and Wyoming).

We further restricted the sample to patients with a new LBP diagnosis between July 2009 and December 2012. We tracked care for patients with a new LBP diagnosis from an “index date” that followed a 6‐month clean period where there were no visits for LBP. LBP was identified using an all‐inclusive list of IDC‐9‐CM codes derived from HEDIS Measures on using imaging studies for LBP and from the literature (Fritz et al. 2012; NCQA 2014). LBP was identified within the primary diagnosis field across the provider, outpatient, and inpatient insurance claims files. Patients with a prior history (within the 6‐month clean period) of LBP, any prior back surgery, or any prior serious diagnoses such as cancer and nonmusculoskeletal reasons for back pain were excluded (see Table S1 for full list of included and excluded ICD‐9‐CM and CPT codes). The index date visit was restricted to the following place of services (POSs): offices, retail clinics, urgent care, outpatient hospitals, EDs, ambulatory surgical centers, independent clinics, federally qualified health centers, and rural health clinics. The final sample size was 148,866 patients.