Functional status (FS) outcomes of patients with lumbar spine dysfunctions managed in outpatient rehabilitation clinics are affected by many variables, including patient demographic variables. 35 Before clinicians can interpret associations between treatments and outcomes in a meaningful way, FS outcomes must be statistically risk-adjusted to control the effect of variables that may or may not be related to clinical care. 8,23,33,35,52 Although statistical risk adjustment models can appear complicated, 53,54 results of these models tend to be clinically logical. For example, it is clinically logical that patients who are older or patients whose symptoms are more chronic should report less FS change compared to patients who are younger or have more acute symptoms, and, indeed, results support this inverse relationship (ie, as patients age, or symptoms become chronic, FS T T STUDY DESIGN: Retrospective analysis of a prospective, longitudinal cohort study of 30 858 patients being treated for a lumbar spine dysfunction in outpatient physical therapy.
T T OBJECTIVES:To determine effect of adding a single-item screening variable classifying patients with elevated versus not-elevated scores of fearavoidance beliefs of physical activities at intake, on a model predicting risk-adjusted functional status (FS) outcomes.
T T BACKGROUND:Outcomes must be risk-adjusted before making meaningful interpretations. Elevated fear-avoidance beliefs scores have been predictive of poor outcomes. But the importance of elevated fear-avoidance scores in a multivariable model predicting FS outcomes needs further study.
T T METHODS:Using retrospective analyses, predictive ability (R 2 ) of multivariable linear regression models of discharge FS with and without classification by elevated versus not-elevated fearavoidance scores were compared, while controlling for intake FS, age, symptom acuity, surgical history, gender, number of comorbidities, and payer. Percent variance controlled and beta coefficients (95% confidence intervals) of each variable in both models were compared. A split-half design was used for model cross-validation. Predictive ratios (predicted FS, divided by actual discharge FS) were assessed.
T T RESULTS:Adding fear-avoidance beliefs classification to the discharge FS model improved (P<.001) model predictive ability but only slightly (R 2 without, and with, fear-avoidance classification, 0.2997 and 0.3010, respectively). Variables impacted models similarly (95% confidence intervals not different). Fear-avoidance classification added 0.2% data variance control to the existing model. Cross-validation was supported. Predictive ratios were 1.09 and 1.10, without and with fearavoidance, respectively.
T T CONCLUSION:Although screening for elevated fear-avoidance beliefs of physical activities significantly improves the FS outcomes predictive model, the amount of additional meaningful interpretation of FS outcomes was minimal. Exploration of other clinically relevant variables designed to improve outcomes prediction is warranted...