Elsevier

The Spine Journal

Volume 19, Issue 4, April 2019, Pages 645-654
The Spine Journal

Clinical Study
The use of STarT back screening tool to predict functional disability outcomes in patients receiving physical therapy for low back pain

https://doi.org/10.1016/j.spinee.2018.10.002Get rights and content

Abstract

BACKGROUND CONTEXT

The STarT Back Screening Tool (SBST) categorizes risk of future disability in patients with low back pain (LBP). Previous studies evaluating the use of SBST in physical therapy (PT) populations do not reflect the ethnic and socioeconomic diversity occurring in clinical practice and lack statistical power to evaluate factors associated with outcomes within each SBST risk category.

PURPOSE

The purpose of this study is to further refine SBST risk categorization for predicting improvements in functional disability with attention toward patient level factors that might guide SBST use in routine outpatient physical therapy practice.

STUDY DESIGN/SETTING

This was a retrospective cohort study that took place within a large academic, tertiary-care health system.

PATIENT SAMPLE

The study cohort consisted of 1,169 patients with LBP who completed a course of outpatient physical therapy from June 1, 2014 to May 31, 2015 and who completed the patient-reported SBST and modified low back pain disability questionnaire (MDQ) questionnaires as part of standard of care.

OUTCOME MEASURES

Improvement in functional disability defined as decrease in 10 or more points in the MDQ.

METHODS

Multivariable logistic regression was performed to evaluate independent predictors of improvement after PT, which included SBST risk category, baseline MDQ, a two-way interaction term between SBST category and baseline MDQ, prior level of function (independent vs. required assistance), demographic characteristics, number of completed PT visits, and duration of PT episode of care. In exploratory analyses, additional two-way interaction terms between SBST category and the significant predictors were added to the regression model.

RESULTS

Mean age of patients in the study cohort was 55.1 years (SD 16.1); 657 (56.2%) were female, 117 (10.0%) were black race, 127 (10.9%) had Medicaid insurance, and 353 (30.2%) had previously received PT for back pain. In all, 35.8% (n=419) patients categorized as low risk SBST category, 40.7% (n=476) medium risk SBST category, and 23.4% (n=274) high risk SBST category. There was an interaction between baseline MDQ and SBST risk category and improvement with PT. For all three SBST categories, higher baseline MDQ was associated with higher probability of improvement, but the effect was less pronounced as SBST risk category increased. Additional factors independently associated with reduced odds of improvement after PT included black race (odds ratio [OR] 0.44, 95% confidence interval [CI] 0.28–0.72), Medicaid insurance (OR=0.58, 95% CI 0.36–0.95), and prior PT (OR=0.48, 95% CI 0.34–0.67). In exploratory analyses, there was a significant interaction between insurance type and SBST risk category in predicting functional improvement after PT. Patients with Medicare and Medicaid insurance had similar rates of improvement in low and high risk SBST categories but different rates of improvement in the medium risk categories.

CONCLUSIONS

The SBST tool predicts outcomes of PT in a cohort of patients receiving outpatient PT for LBP. The odds of improvement varied according to baseline disability and SBST risk status. Race, insurance type, and history of previous PT influenced prediction independent of SBST risk status. Incorporating these variables and the interaction between SBST and baseline disability in outcome models has the potential to refine prediction of outcomes after PT.

Introduction

Back pain is one of the most common health problems with more than two-thirds of the population reporting back pain at least once during life [1], [2]. Low back problems are the second and third leading complaint in outpatient visits and hospital admissions respectively [1], [3] and carry an annual prevalence of as high as 45% [4]. The high incidence and prevalence of back pain equates to substantial health care utilization and spending. In 2005 in the US, the direct health care costs of back pain were estimated at 85 billion dollars [5], [6]. More concerning is that these cost has increased by 65% since 1995 at a rate far outpacing overall healthcare spending [5], [6], [7].

At least 25% of outpatient physical therapy practice is related to low back pain (LBP) [8], [9], [10]. The American College of Physicians practice guidelines recommend many nonpharmacologic interventions used by physical therapists as front line LBP treatments [11]. However, 45% of patients receiving physical therapy fail to have significant improvement in pain and disability [12]. Early identification of those with favorable and nonfavorable prognoses could have a significant impact on future care models for LBP. In particular, emotional dimensions are important contributors to outcomes of patients with LBP. The STarT Back Screening Tool (SBST) [13] is one well-established clinical tool used to determine risk of future disability based on psychosocial factors. It was originally designed for use in primary care [14], where providing risk-stratified treatment improved disability outcomes while lowering healthcare utilization when compared to usual care [15]. The SBST has also been used to successfully predict disability outcomes for patients seeking outpatient physical therapy [16], [17].

There are still areas to explore for gaining a better understanding of the SBSTs predictive capabilities, in order to improve their utility in clinical practice. Previous studies have focused on differences in clinical outcomes between the three risk groups, because they lacked adequate statistical power to refine predictive accuracy within an individual risk group. Prior investigations were recruited as part of clinical trials or cohort studies, and may not reflect ethnic and socioeconomic diversity occurring in real practice settings. Future investigation of these factors is needed as highlighted by a recent analysis indicating individuals with greater psychosocial distress and lower socioeconomic status (SES) had decreased benefit of receiving risk stratified care [18]. Therefore, the overall purpose of this study to further refine SBST risk categorization for predicting improvements in disability in a multivariable model with attention toward patient level factors that might guide SBST use in routine outpatient physical therapy practice. First, we determined the association of SBST categorization with meeting a clinically meaningful improvement threshold for functional disability, as determined by the patient-reported modified low back pain disability questionnaire (MDQ). Second, we investigated whether there was an interaction between SBST risk category and baseline functional disability to provide better context in predicting improvement. Information from this analysis will optimize the use of SBST within clinical practice.

Section snippets

Study design

This was a retrospective cohort study of patients with LBP who presented for outpatient physical therapy at Cleveland Clinic Health System facilities in northeastern Ohio. In this system, patient-reported outcomes are systematically collected at the point of care on tablets at all physical therapy sites through the Knowledge Program data collection system [19]. Results are immediately available within the electronic health record (Epic, Epic Corporation, Verona, WI, USA). SBST and MDQ were both

Patient characteristics

A total of 10,329 patients had a PT episode of care between June 1, 2014 and May 31, 2015 with a primary ICD-9-CM diagnosis code for a LBP and were 18 years of age or older at their first visit. We removed 287 patients who were missing documentation indicating their episode of care was complete and an additional 6,130 patients who did not complete the SBST. Finally, we removed 2,743 patients who did not have an MDQ at baseline and follow-up. Thus, our final sample consisted of 1,169 patients (

Discussion

Our analyses demonstrated a potentially complex relationship between SBST category, disability score, and improvement. The interaction between SBST category and baseline MDQ score is a novel finding with clinical relevance, as our findings indicated that the relationship between SBST category and meaningful improvement in disability varied according to baseline MDQ scores. Among patients with lower baseline disability (MDQ scores <20), those categorized as low psychosocial risk had lower

Conclusion

This analysis has shown that SBST tool predicts outcomes of PT in a real world cohort of patients receiving outpatient physical therapy for LBP. We identified nuances that may refine future SBST use. First, there was an interaction indicating that odds of improvement varied according to baseline disability and SBST risk status. Second, we identified race, insurance type, and history of previous PT as variables that improved prediction independent of SBST risk status. Incorporating these

Acknowledgment

Dr. George acknowledges funding from the National Institutes of Health/National Center for Complementary and Integrative Health (UG3AT009790) in preparation of this manuscript.

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    Author disclosures: IK: Nothing to disclose. NT: Nothing to disclose. SG: Nothing to disclose. SP: Nothing to disclose. FF: Nothing to disclose. MS: Nothing to disclose.

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