Appendix Table 1.

Overview of Analyses, Statistical Methods, and Scale and Timing of Measuresa

Analysis
Propensity Score MatchingPrimary Outcomes AssessmentSecondary Outcomes AssessmentSensitivity Analyses
Logistic RegressionGeneralized Estimating EquationsCox Proportional Hazards RegressionGeneralized Estimating Equations
MeasureScaleTiming (months)Variable typeVariable typeVariable typeVariable type
AgeCategorical0IndependentNIANIANIA
GenderDichotomous0IndependentNIANIANIA
RaceCategorical0IndependentNIANIANIA
Duration of LBPCategorical0IndependentNIANIANIA
Pain catastrophizingCategorical0IndependentNIANIANIA
Pain self-efficacyCategorical0IndependentNIANIANIA
Chronic widespread painDichotomous0IndependentNIANIANIA
Ever had work loss ≥1 month due to LBPDichotomous0IndependentNIANIANIA
Ever received disability or workers' compensation benefits due to LBPDichotomous0IndependentNIANIANIA
Ever filed a law suit or legal claim due to LBPDichotomous0IndependentNIANIANIA
Prior low back surgeryDichotomous0IndependentNIANIANIA
Health-related quality of lifeContinuous0IndependentNIANIANIA
LBP intensity (NRS)Continuous0, 3, 6, 9, 12IndependentDependentNIADependent
Back-related disability (RMDQ)Continuous0, 3, 6, 9, 12IndependentDependentNIADependent
Pain impact (PI)Continuous0, 3, 6, 9, 12IndependentDependentNIADependent
MIC - NRSDichotomous0, 3, 6, 9, 12NIANIADependentNIA
MIC - RMDQDichotomous0, 3, 6, 9, 12NIANIADependentNIA
MIC - PIDichotomous0, 3, 6, 9, 12NIANIADependentNIA
LTOT (initial assignment to LTOT or control group)Dichotomous0, 3DependentIndependentIndependentIndependent
LTOT (continuous opioid use, defined as 0, 3, 6, 9, or 12 months)Categorical0, 3, 6, 9, 12NIAIndependentIndependentIndependent
LTOT (dose response, defined as 0, 1, 2, 3, or 4 quarters of opioid use)Categorical0, 3, 6, 9, 12NIAIndependentIndependentIndependent
LTOT (dose response, defined as number of MMEs used at baseline)Continuous0NIAIndependentIndependentIndependent
LTOT (continuous opioid use or abstention for 12 months)Dichotomous0, 3, 6, 9, 12NIAIndependentIndependentIndependent

  • ↵Abbreviations: LBP, low back pain; LTOT, long-term opioid therapy; MIC, minimally important change; MME, morphine milligram equivalent; NIA, not included in analysis; NRS, numerical rating scale; PI, pain impact; RMDQ, Roland-Morris Disability Questionnaire.

  • Note: aParticipants in the control group were classified as having no opioid exposure or dose in all analyses.