Table 1.

Description of and Rationale for Predictors Entered Into Logistic Regression Models for Predicting Musculoskeletal Pain Persistent for 12 Months^a.

Model	Predictors Entered	Rationale
Block 1	Demographic	To account for relevant demographic (age, sex, race, household income, education level, and geographic region) variables.
	Clinical	To account for relevant clinical (anatomical location of pain, previous episodes, and surgical history) variables.
	Comorbidityb	To account for no. of medical comorbidities.
Block 2	Baseline persistent pain	To account for pain-related clinical variables.
	Baseline pain intensity
Block 3	OSPRO-ROS (10 items)	To account for brief versions of OSPRO tools.
	OSPRO-YF (10 items)
Block 4	OSPRO-ROS + additional 13 itemsc	To account for additional items in longer versions of OSPRO tools.
	OSPRO-YF + additional 7 itemsc
Block 5	Pain intensity (4-wk change)	To account for changes in baseline pain intensity at 4 wk.
	OSPRO-YF (10 items) (4-wk change)	To account for changes in OSPRO-YF tool at 4 wk.
	OSPRO-YF + additional 7 itemsc (4-wk change)
Block 6	Baseline persistent pain interactions	To account for influence of OSPRO-ROS and OSPRO-YF tools on the basis of baseline persistent pain status.
All models reported with completed cases
Full model (with all covariates)		To determine predictive capabilities of OSPRO tools after accounting for planned covariates.
Parsimonious model 1 (after block 4)		To determine best-fit model after accounting for planned covariates.
Parsimonious model 2 (after block 6)		To determine best-fit model after accounting for planned covariates, change scores, and OSPRO tool × baseline persistent pain interactions.

^aOSPRO = Optimal Screening for Prediction of Referral and Outcome, OSPRO-ROS = OSPRO Review of Systems, OSPRO-YF = OSPRO Yellow Flag.

^bComorbidity data included composite counts (0, 1, or ≥2) from the Charlson Comorbidity Index and the Functional Comorbidity Index. Pain intensity was measured with a numerical pain rating scale from 0 to 10.

^cAdditional items were from longer versions of the corresponding tool.