Response Shift After a 4-Week Multimodal Intervention for Chronic Ankle Instability

Chronic ankle instability (CAI) is a condition characterized by residual symptoms, recurrent ankle sprains, and repeated episodes of the ankle “giving way” during functional activities.¹ The repetitive trauma that accompanies CAI is believed to contribute to long-term consequences, such as ankle osteoarthritis² and reduced physical activity.³ Traditionally, CAI investigations have focused on identifying mechanical and sensorimotor deficits from a disease-oriented perspective, such as dorsiflexion range-of-motion restrictions⁴ and postural-control impairments.⁵ However, the emergence of evidence-based practice has emphasized the importance of patient-oriented evidence that evaluates the effect of a condition or treatment on health status from the patient's perspective. This, coupled with the directive from the International Ankle Consortium⁶ to include patient-reported outcomes (PROs) in CAI research, has led to an increased number of studies that incorporate these instruments.

Within clinical practice, accurately determining patient changes using PROs is vital for evaluating patient progression and making subsequent clinical decisions.⁷ Given the subjective nature of the information captured by PROs, researchers have assumed that the intraindividual standards remain stable throughout rehabilitation for measuring true change in these concepts.^8,9 However, this may not be a correct assumption, as patient values can vary as they reconceptualize their conditions during the disease or rehabilitation process.^8,9 This reconceptualization is known as response shift (RS) and can alter the manifestation of perceived health-related quality of life (HRQOL).⁹ Response shift is a phenomenon by which an individual's self-evaluation of a construct changes due to a change in the internal standards of measurement (scale recalibration), a change in values or priorities (reprioritization), or a personal redefinition of the target construct (reconceptualization) or a combination of these.^8,9 Consequently, an RS may interfere with the ability to accurately detect change in a construct or PRO, leading to improper clinical decisions if encountered during the treatment process.

Traditionally, RS has been observed in individuals with chronic, life-threatening conditions whose physical health deteriorates but whose self-reported HRQOL remains stable.¹⁰ More recently, RS has gained attention as a possible phenomenon¹¹ after rotator cuff repair,¹² autologous chondrocyte implantation,¹³ total knee arthroplasty,^14–16 knee microfracture,¹⁷ lumbar spinal decompression surgery,¹⁸ and unspecified rehabilitation for chronic low back pain,¹⁹ all treatments for chronic musculoskeletal conditions. Response shifts in these populations can potentially affect the evaluation of the rehabilitation process and clinical decision making and lead to the underestimation or overestimation of patient change after treatment. Subsequently, inaccurate assessments of patient change could lead to improper progression, continuation, or cessation of a treatment course.

Individuals with CAI may follow a trend similar to that of patients with chronic low back pain¹⁹ after conservative rehabilitation. Like chronic low back pain, CAI is a condition associated with prolonged modifications in physical activity to avoid reinjury.^3,20 Therefore, if individuals with CAI reconceptualize their health by avoiding activities that promote giving way or have instigated previous ankle sprains, this may affect subsequent treatment decisions and negatively affect rehabilitation progression. Therefore, the purpose of our study was to evaluate the RS phenomenon among individuals with CAI after a 4-week rehabilitation program. We hypothesized that RS would occur and would indicate that detriments in HRQOL may be underestimated in individuals with CAI before rehabilitation.

METHODS

Design

In this controlled laboratory study, all participants completed 4 data-collection sessions (baseline, preintervention, postintervention, and 2-week follow-up) at which PROs were collected and a 4-week intervention (Figure 1). The 4-week intervention consisted of 12 supervised sessions and a daily home-exercise protocol. The PROs were collected traditionally: perceived function was evaluated at the time of PRO completion and with the then-test method, which is a retrospective evaluation of perceived function before the intervention that is completed after the intervention. The independent variables were time (baseline, preintervention, postintervention, 2-week follow-up) and PRO administration (traditional, then test). The dependent variables were PRO scores.

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RESULTS

The mean (± standard deviation), Cronbach α, and MDC for the preintervention and then-test assessments are displayed in Table 1, and the ESs and 95% CIs are displayed in Figure 2. Overall, 0.22% of all PRO data was imputed using regression imputation due to missing items.²¹

Table 1 Preintervention and Then-Test Assessments (Mean ± SD), Cronbach α, and Minimal Detectable Change^a

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Assessment of Response Shift

When assessing the presence of an RS after the intervention, no differences were detected between preintervention and then-test postintervention or then-test follow-up scores for any PROs (F values > 2.338, P values > .12). These differences did not exceed the MDC²¹ (Table 1) and were associated with weak ESs and CIs that crossed zero (Figure 2). The number of participants who had preintervention to then-test postintervention and then-test follow-up changes that exceeded the calculated MDCs is presented in Table 2. The FAAM-Sport subscale had the largest number of participants with individual-level RSs that indicated greater reported disability on the then-test postintervention (n = 5, 25%) and then-test follow-up (n = 5, 25%) evaluations. The FABQ Physical Activity subscale had the largest number of participants with individual-level RSs that indicated less disability on the then-test postintervention (n = 6, 30%) and then-test follow-up (n = 6, 30%) evaluations. Overall, these findings indicated the lack of a meaningful RS or recalibration of the participants' internal standards.

Table 2 Individual-Level Response-Shift Analysis (Rate [%])

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DISCUSSION

We hypothesized that individuals with CAI who participated in a 4-week multimodal rehabilitation program would experience RSs that would result in initially underestimating their HRQOL detriments before rehabilitation as determined by then-test assessments associated with greater levels of disability than at preintervention. Our findings did not support this hypothesis, as we observed no differences between preintervention and then-test postintervention or between preintervention and then-test follow-up measures. This indicates that at postintervention, the participants' retrospective assessments of their disabilities before the intervention were similar to their preintervention measurements at the group level. These findings further suggest that after conservative care, patients with CAI did not experience an RS and that traditional preassessment-to-postassessment testing methods provided an accurate evaluation of the treatment effect.

This investigation was one of the first to evaluate the RS phenomenon after a conservative intervention. Nagl and Farin¹⁹ evaluated the effect of RSs in individuals undergoing conservative rehabilitation for low back pain. Whereas their conclusions indicated that an RS in which individuals underestimated their preintervention disability had occurred, these results were associated with weak ESs,¹⁹ suggesting that their identified RS may not have been clinically meaningful. This would support our observations that individuals with CAI did not experience RSs, as we found nonsignificant differences that were associated with weak ESs for all measures. Sprangers and Schwartz⁹ proposed that a substantial catalyst is required for an RS to occur. Traditionally, RSs have been identified after surgical interventions, such as knee replacement,¹⁶ rotator cuff repair,¹² and arthroplasty.¹⁴ Conservative care may not provide a substantial enough catalyst to prime individuals for an RS.¹¹ As such, our findings support using traditional preassessment-to-postassessment comparison methods to evaluate self-reported function after a conservative intervention for those with CAI. However, this should not be assumed for all treatment courses among patients with CAI. Researchers should evaluate the potential for an RS after surgical intervention, such as lateral ankle repair, among those with CAI.

Individual-level examination of RSs was conducted by determining the number of participants with differences between preintervention and then-test scores that exceeded calculated MDCs.²¹ The FAAM-Sport subscale and FABQ Physical Activity subscale scores exhibited the greatest levels of potential individual-level RSs, as an average of 7 (35%) individuals demonstrated differences that exceeded the MDC (Table 2). However, only 5 participants had evidence of RSs on both instruments. Therefore, the RS may be construct specific for an individual patient and not serializable across domains of function and contextual factors. The modified Disablement in the Physically Active scale mental summary component and the FABQ Work subscale scores displayed the lowest levels of potential RS, as the magnitudes of an average of 3 (15%) individuals exceeded the MDC. Furthermore, PROs that demonstrated greater levels of potential individual-level RSs were associated with preintervention-to-postintervention changes.²¹ Similarly, PROs that demonstrated lower levels of potential individual-level RSs were associated with a lack of preintervention-to-postintervention changes.²¹ In combination, these results may indicate that the potential for RS is greatest in outcome measures that are meaningful to patients and display large amounts of change after an intervention. In addition, 3 (15%) participants at postintervention and 5 (25%) participants at the 2-week follow-up demonstrated RS magnitudes that exceeded the MDC for at least 3 of the 6 PROs. These individual-level findings are similar to those from a previous investigation¹³ of RS after autologous chondrocyte implantation that demonstrated individual-level RSs ranging from approximately 20% to approximately 40% of the participants. Furthermore, 17% to 31% of these participants displayed RSs on 3 of the 4 PROs, and the authors¹³ did not identify group-level RSs similar to those in our investigation. Lastly, we found that for each PRO, participants exhibited an RS recalibration that demonstrated both an overestimation and underestimation of their preintervention function, which was similar to the results of Howard et al.¹³ This incongruence may have contributed to our lack of group-level findings. Ultimately, we did not identify a group-level RS, but we did note low levels of individual RSs. At this time, it is unclear if this level of RS could affect the assessment of patient change in the clinical setting. Further research is needed to explore the effects of potential individual-level RSs on the assessment of patient change and to determine when RS is most likely to occur in populations with a variety of orthopaedic conditions. Innovative and clinician-friendly techniques for assessing individual-level RSs should also be evaluated.

Our investigation had limitations. The major limitations were the lack of a true control group and our relatively short follow-up period of 2 weeks. Time is possibly a factor in evaluating RSs, as many researchers' follow-up periods were 6 to 24 months.^12–15 Participants may need more time to reconceptualize their new level of function, as well as to be exposed to challenging tasks or situations. Also, our participants were not actively seeking care for their ankle conditions at the time of the study, which may have affected their potential for an RS. In previous studies,^13,16,18,19 researchers examining RS have investigated patient groups who were actively seeking health care services in the form of surgery or rehabilitation for their health conditions. Future work is needed to confirm and expand on our findings by including blinding and sham treatments, a longer follow-up period, and participants who are actively seeking treatment. Finally, this study was not powered to observe an RS. Based on our findings, future RS investigations should include between 10 (ES = 0.56) and 51 (ES = 0.23) participants, as indicated by our primary outcomes.

CONCLUSIONS

The results of this research support using traditional preassessment-to-postassessment methods to evaluate the efficacy of conservative treatment for patients with CAI, as no group-level RS was observed. However, some individuals with CAI may demonstrate individual-level RSs. Clinicians may need to develop patient-centered methods of evaluating the potential for RS in their patients when providing individualized care. Not evaluating individual-level RSs in the clinical setting could result in an inaccurate evaluation of patient-reported change during rehabilitation.