Comparing Ways to Treat Low Back Pain and Prevent Chronic Pain and Disability—The TARGET Trial [Internet]

Excerpt

Background: A large proportion of patients experiencing acute low back pain (LBP) initially seek care from their primary care providers (PCPs). Clinical practice guidelines recommend that patients with acute (recent-onset) LBP be provided with nonpharmacological treatment and discourage early diagnostic and intervention procedures. However, the implementation of clinical practice guidelines at the PCP level and in physical therapy care continues at suboptimal rates. Stratification tools, which include questionnaires that divide patients into categories of high, moderate, or low risk, can help identify patients who, because they are at high risk for persistent disabling LBP, may have the most to benefit from patient-centered interventions. Our research question was, therefore, for high-risk patients presenting with acute LBP, should prompt referral to a stratified approach to physical therapy care be recommended to prevent a transition to chronic LBP?

Objectives: Our original objectives were (1) to compare the rate of transition to chronic LBP when high-risk patients receive usual care (UC) or a stratified approach to care; and (2) to estimate the rate and predictors of transition to chronic LBP among patients deemed low to medium risk. Due to the higher-than-expected nonresponse for the primary outcome, PCORI imposed a modification of the study objectives and, hence, the contractual agreement between PCORI and the study sponsor, the University of Pittsburgh. The modified objectives were to estimate the rate of transition to chronic LBP and average back-related physical function with UC and with a stratified approach to care (UC plus referral to psychologically informed physical therapy [UC+PIPT]) among patients presenting to primary care clinics with acute LBP and deemed high risk. For the patients deemed medium and low risk, we sought to estimate the rate of transition to chronic LBP and health care use and to determine the factors associated with these outcomes. PCORI officials believed that the limitations of (1) lower-than-expected response rates coupled with (2) limited treatment integrity did not warrant the use of inferential statistical approaches, a stance with which the Targeted Interventions to Prevent Chronic Low Back Pain in High-Risk Patients (TARGET) trial investigators disagreed. Thus, the aims were modified to reflect the descriptive approach imposed by PCORI.

Methods: This study used 2 simultaneous research designs in primary care clinics of 5 large US academic health care systems to meet the objectives among patients presenting to primary care for acute LBP. Patients with acute LBP at all clinics were risk stratified (high, medium, low) using the Subgroups for Targeted Treatment (STarT) Back Screening Tool. For the first objective among patients deemed high risk for persistent disabling symptoms, we used a cluster randomized controlled trial (RCT) where, ultimately, 76 primary care clinics were randomized to UC+PIPT or UC. To address the second objective, we used an observational cohort for those patients who screened low to medium risk on the STarT Back Screening Tool. Originally, the planned study sample size was 2880, which was based on a nonresponse rate of 8%, 60 randomized clinics, and 90% power to detect a relative reduction of chronic LBP of 40%. During recruitment, we revised the expected sample size to an average of 31 enrolled high-risk patients per clinic (60 × 31 = 1860), 80% power, and assuming a 40% nonresponse rate at 6 months. In the intervention group (UC+PIPT), we assumed that the best-practice alert, which is a clinician decision support tool available in the electronic medical record (EMR) when a particular element of a patient's care needs additional attention, would be executed as a rule (we did not hypothesize a percentage adherence to the alert). The primary outcomes were the transition from acute to chronic LBP and LBP-related functional disability as determined by the Oswestry Disability Index (Oswestry) at 6 months. Secondary outcomes were LBP-related processes of health care and use of services over 12 months, as obtained from EMRs. Generalized linear mixed models were used to estimate the proportion of patients who transitioned to chronic LBP and mean functional disability at 6 months, along with corresponding confidence intervals adjusting for the clustered design. These models were also used to assess factors associated with the transition to chronic LBP and resource use among low- to medium-risk patients.

Results: The nonresponse rate for the primary outcomes at 6 months was 40%. Among high-risk patients in the cluster RCT, approximately half reported chronic LBP at 6 months (UC+PIPT group [n = 658]: 47%; 95% CI, 42%-51%; UC group [n = 635]: 51%; 95% CI, 46%-56%). Thirty-nine percent of patients in the UC+PIPT group received a referral for PIPT; <1% of patients in the UC group received a referral for PIPT. Both groups reported moderate disability at 6 months, with average Oswestry scores of 27 (95% CI, 25-29) and 30 (95% CI, 28-32) for UC+PIPT and UC, respectively. About 1 in 4 patients were prescribed opioids at the index visit. Nearly half of both groups had primary care visits for LBP over 12 months, 15% to 18% had a visit to a specialist, 17% to 19% received imaging, and <5% had interventional pain procedures, such as epidural steroid injections. Fewer than 3% had surgery in either group. In the observational cohort of low- and medium-risk patients, we recruited 3524 and 3847 patients, respectively. About 1 in 5 low-risk patients reported chronic LBP at 6 months (19%; 95% CI, 16%-21%) compared with 33% of the medium-risk patients (95% CI, 30%-35%). Health insurance (eg, Medicaid vs all others), obesity, smoking, baseline disability, and several processes of care at the index visit were associated with higher rates of chronic LBP at 6 months in the low- and medium-risk patients. About 9% of low-risk and 15% of medium-risk patients underwent imaging during the 12 months.

Conclusions: In a multisite US health care setting, a comprehensive intervention (UC+PIPT) to support stratified care for LBP targeting high-risk patients that included numerous implementation strategies in primary care and physical therapy did not reduce the transition from acute to chronic LBP. Patients in both groups had a higher-than-expected transition to chronic LBP. The rates of diagnostic testing and interventional pain procedures were relatively low. The stratification tool successfully identified groups at lowest and highest risk for transition to chronic LBP.

Limitations: This study has 2 major limitations: (1) limited treatment fidelity reflected in the low rate of PIPT referrals and (2) high nonresponse of the primary outcome at 6 months that was similar across risk strata. Although the nonresponse rate was about 40% at 6 months, there were no clinically meaningful differences in baseline characteristics between those who responded and those who did not.