The goal of this narrative review was to describe the findings of studies using the SBT in chiropractic settings. To date, no other reviews of this nature have been conducted. The findings suggest that it’s feasible to incorporate the SBT into chiropractic clinical settings [17] but that the short episode duration at onset of care (<2 weeks) with which many chiropractic patients present may be a barrier to the SBT’s predictive ability in some patients [9, 18, 21].
The Field and Newell [18] results indicate that high risk chiropractic patients may improve so quickly that there aren’t strong associations with SBT risk and poor outcomes. These results also suggest that there may be differences in patients with high risk in chiropractic settings compared to patients with high risk in primary care medical settings.
The Kongsted et al. [9] study revealed statistical association between the SBT score and long-lasting symptoms, but both clinicians’ and SBT predicted only 11 and 10% of patients, respectively, who would be pain free within 2 weeks of chiropractic care. This indicated poor predictive ability in both clinicians and SBT for short-term outcomes. The researchers in this study dichotomized the pain and disability variables, designating anything greater than 0 out of 10 on a pain scale or 8 out of 100 activity limitation as “poor outcomes.” This is quite a stringent standard, particularly in studying LBP; being completely pain free after 2 weeks of care isn’t a pragmatic goal and is beyond what is considered a clinically important improvement according to these outcome measures (the minimal clinically important difference ranges from 1.5 to 3.5 points of change for the NRS and 2.5 to 5 points of change for the RMDQ) [23–26]. Some patients in this study may have had clinically important improvements within 2 weeks (or later) but that data would have been lost in dichotomizing the outcome variables. Furthermore, though a greater percentage of clinicians compared to SBT accurately predicted which patients would have a long-lasting duration of symptoms, both predicted accurately more than 50% of the time for that variable. The SBT was weakest at predicting outcomes in participants who had a short duration of the LBP episode at onset of care, which describes a large percentage of the participants in this study.
The Morso et al. study results [21] suggest that short episode duration (<2 weeks) limits the SBT’s predictive ability across multiple care settings. The association between short duration and weak SBT prognostic accuracy may have played a role in the low prognostic utility in the Field and Newell [18] and Kongsted et al. [9] studies as well [9, 21, 18], although further studies are needed to better elucidate this phenomenon.
Since chiropractic settings showed the greatest percentage of short-duration episodes relative to other health care settings [21], chiropractors should be cautious when using the SBT on short episode duration patients. However, caution must also be exercised when interpreting mean group correlations, because the SBT may still be predictive in some short episode duration patients, as seen in the Newell et al. [20] study, despite not being associated with mean group outcomes.
Factors other than episode duration may also affect the SBT’s predictive ability. The Newell et al. [20] study demonstrated that the SBT was predictive in some patients who completed it 2 days after their initial treatment visit instead of at baseline. A study by Beneciuk et al. [27] also demonstrated that socioeconomic status, education level, and number of pain medications may affect the SBT’s predictive ability in medical care settings [28]. Research conducted in countries and subpopulations that differ from the 7 reviewed care settings will be important in better understanding the SBT’s predictive ability and utility for improving outcomes in patients seeking chiropractic care.
Other aspects of these studies also warrant attention. For example, a limitation of the Field and Newell [18] study is that participant data wasn’t collected beyond 3 months. Six and 12-month follow-up data would be valuable to see if a stronger correlation between SBT score and future prognosis existed at those time points. A limitation of the Field and Newell [18], Newell et al. [20], Kongsted et al. [9] and Morso et al. [21] studies is that the patients self-selected clinics in which they were treated. Self-selection may have ruled out many psychological barriers to improvement at the outset. Also, in the Field and Newell [18] study, roughly 41% of patients had been to the treating chiropractor in the past, which may have lead to greater expectation of improvement [18, 29, 30]. Future studies using the SBT might evaluate patients’ previous experience with manual therapy for their back pain and how expectations may affect outcomes.
Attending a course of manipulation may reduce psychological outcomes such as depression and mental component scores [19]. It’s possible that the inherent overlap between chiropractic treatment and the stratified care approach used in the STarT Back protocol altered outcomes in the studies examined in this review. Though the chiropractors in these studies were treating patients as usual and weren’t privy to patients’ SBT score, they may have altered or tailored their care based on clinical expertise and cues from patients about their psychological state, which is a stratification of sorts. This may have affected outcomes in ways that warrant further study.
All 7 reviewed studies were conducted in European populations (Denmark, Norway, and the UK) [9, 18–21, 22]. In the UK, it is unusual for chiropractic to be included in the state-funded health care system [27] and in Denmark only about 20% of costs are covered by the national health insurance [9]. Patients who seek chiropractic care in these countries may be in different socioeconomic strata than those in the general LBP population, or may have a different psychosocial risk profile from other countries [22, 27], which may affect the SBT’s predictive utility [28]. As demonstrated in the Field and Newell (2016) study [22], there also may be significant differences in patients who are self-referring for chiropractic care compared to those referred by general practitioners [27].
Furthermore, in the Irgens study [22], there was a statistically significant difference between the psychosocial risk profile in English versus Norwegian patients. Norwegian participants were younger, less distressed by their condition, and had lower catastrophization and depression, but were slightly more anxious than the UK participants studied. This lends further credence to the idea that the results of the reviewed studies may not be generalizable to patients in other countries where parallel analyses haven’t been conducted. Psychosocial risk profiles in other populations may differ enough to change the predictive ability of the SBT, or the outcome effects of stratified care pathways [22, 27].
However, none of the studies in this review implemented or examined STarT Back stratified care pathways. For patients who score in the low risk category, The STarT Back Protocol provides nothing more than a session of home advice, education about pain, and encouragement to continue physical activity [6]. Specific chiropractic treatment duration wasn’t described in these studies, except that treatment plans were unaffected by SBT categorization. It’s possible that some patients received minimal care, but it’s unknown. It’s not possible at this time to compare outcomes of usual chiropractic care to the SBT care pathway for low risk patients seeking chiropractic care. At present, the SBT remains a valuable tool for detecting low risk patients who may achieve comparable outcomes from one session of patient education and home exercises, instead of a course of spinal manipulation [5, 6, 12, 13].
Although the SBT was first developed to aid primary care medical physicians in determining best care pathways for patients with LBP, the SBT may be useful in stratifying care pathways for chiropractic clinicians. In many countries such as the US, Canada, and Great Britain, doctors of chiropractic are primary-contact providers [22, 31, 32]. Patients seeking care in chiropractic settings may benefit from stratified care in similar ways to those seeking medical care [5, 13] but, as demonstrated in this review, stratified care hasn’t yet been studied in chiropractic settings.
This review offers an assimilation of studies using the SBT in a chiropractic setting, but a number of limitations exist. First, this was a narrative review, so systematic methods of quality appraisal were not applied when selecting and reviewing manuscripts, and some articles may have been missed. One study was a secondary analysis, and no randomized controlled trials were available at the time of review. Therefore the strength of available evidence was low. Finally, letters to editors, conference proceedings, and other non-peer reviewed articles were excluded, which may have resulted in neglecting relevant information and discourse.
Future research
Although the SBT lacked strong predictive value in short episode duration patients, perhaps a better focus for future research would be to explore the outcomes of stratified care in a broad range of chiropractic settings, particularly in light of the stratified care benefits reported in primary care medical settings [5, 13]. As the Morso et al. [21] study concluded, “the real potential of the SBT is as a tool for stratifying care pathways and therefore clinical trials are required to determine if the SBT is useful in chiropractic and secondary settings.”