Interoceptive bodily awareness in patients seeking pain relief with osteopathic manipulative treatment: an observational cohort pilot study

Ethical approval and population

Our study was approved by the Touro University California College of Osteopathic Medicine (TUCCOM) Institutional Review Board (IRB #FWA00009823). A convenience sample was recruited at the university’s OMT Teaching Clinic, where OMT is provided free-of-charge to the campus community by predoctoral fellows in Osteopathic Manipulative Medicine (OMM) and precepted by osteopathic physician faculty board-certified in neuromuscular medicine/osteopathic manipulative medicine (NMM/OMM). Between January and April 2019, study staff screened potential participants on arrival to the clinic, and informed consent was obtained utilizing paper forms. Participants were compensated with $10 gift cards after completing surveys at each time point. Funding was provided by TUCCOM.

Study design

This single-arm observational cohort pilot study recruited participants into two groups, OMT-naïve and OMT-experienced. In prior studies of mind–body interventions that showed an association with changes in MAIA scores, intervention doses were much higher (1–3 sessions/week of contemplative training for 8 weeks or longer [31]) than our single OMT session in this pilot study. Thus, expecting that we may not observe changes in MAIA scores after a single OMT session, we a priori split our sample according to previsit exposure levels to determine potential cumulative changes in MAIA scores associated with ‘a higher dose’ of total OMT exposure.

The primary outcome in this study was IBA assessed by the MAIA-2. Secondary outcomes were pain intensity, pain interference, and participant’s perception of change post-OMT. Although mindful attentional states have been shown to be associated with clinical outcomes such as pain intensity [13], pain prognosis [49], and depression [33], prior studies did not determine a clinically meaningful change in IBA, or effect size. For this pilot study, we aimed to enroll 30 to 40 participants.

Inclusion criteria were: 18 years of age or older, seeking OMT for the relief of pain, qualifying as either “OMT-naive” (no OMT sessions in the past 3 months, <3 total lifetime sessions) or “OMT-experienced” (at least 1 OMT session in the past 3 months, >5 total lifetime sessions), willingness to stay after the appointment to complete the post-OMT survey, and willingness to respond to follow-up email surveys within 3 days of receiving. Exclusion criteria were: unable to read and write in English, and having already participated in this OMT study.

Patients presenting to the OMT clinic were approached by the study staff seated at the front desk, which was located down the hall from the treatment rooms. The front-desk study staff screened and enrolled interested and eligible participants. OMT practitioners (fellows and faculty preceptors) remained in their treatment rooms between patients to avoid seeing whether their next scheduled patient was performing enrollment paperwork. All fellows were aware that the study was occurring (however, they were not aware of the objectives or hypotheses) to adhere to the blinding procedures of remaining in their rooms, and all patients received OMT as usual care regardless of study enrollment status. Patients were instructed not to disclose their study participation status to the OMT practitioners. If OMT practitioners became unblinded to their patient’s study participation status, this participant was flagged so that their data could be excluded from analysis.

Measures

Descriptive data were collected at baseline via questionnaire. All questionnaires were collected securely through Research Electronic Data Capture (REDCap). Questionnaires were administered at four time points: immediately before and after the OMT session on study laptops in the clinic, and at 1- and 3-weeks follow-up via secure email.

MAIA-2 was administered at each time point. The MAIA-2 is a 37-item questionnaire that assesses IBA across the following eight distinct but related domains: noticing, not distracting, not worrying, attention regulation, emotional awareness, self-regulation, body listening, and trusting. Higher scores on the MAIA-2 questionnaire imply higher levels of IBA. The MAIA has shown acceptable internal consistency reliability (alpha range 0.66–0.82), good discrimination between known groups, and good sensitivity to change in longitudinal studies [50].

Pain was assessed at each time point with the Numeric Rating Scale (0=no pain; 10=worst imaginable pain), and the impact of pain on daily functional status was assessed with the four-item Patient-Reported Outcomes Measurement Information System (PROMIS)-SF4a Pain Interference Scale. The Global Rating of Change (GRC) scale was assessed at each follow-up time point. This scale provides an opportunity for participants to integrate their impression of improvement [51]. The Numerical Rating Scale (NRS), PROMIS, and GRC have been recommended as core outcome measures in chronic pain trials and have been validated, having shown acceptable internal consistency and reliability [52, 53].

We chose to capture prior experience with mind–body activities that have an association with MAIA scores [48]. Given the known interrelated neurophysiology of touch and interoception [54, 55], we also captured experience with the non-OMT body work. All experience questions were answered on a 0–10 scale (0=no experience, 10=highly experienced). Given the relationship between traumatic experiences, interoception, and body-based trauma therapies [56], we collected data on the extent and timing of exposure to both physical and emotional trauma. Exposure to trauma questions were answered on a 0–10 scale (0=none, 10=many times and/or a major event).

Analyses

Our research questions were: are there differences in baseline levels of IBA as measured by the MAIA-2 based on historical exposure to OMT? Are there differences in IBA as measured by the MAIA-2 before and after a single OMT appointment? Are changes in clinical outcomes (pain interference, pain intensity, patient’s global impression of change) associated with changes in IBA? In addition, in exploratory analyses, we examined whether potential covariates (exposure to mind–body practices, exposure to body work, exposure to trauma, pain interference, pain intensity, and patient’s global impression of change) play a role in associations between OMT and IBA. We utilized Stata Statistical Software Version 15.1 (StataCorp LLC, College Station, TX).

For scoring the MAIA-2 scales, we utilized the instructions as laid forth in the MAIA-2 questionnaire [47]. If a scale had less than 50 % of item responses, we did not utilize the score for that scale.

To investigate whether there were differences in baseline levels of IBA between OMT-naive and OMT-experienced participants, we conducted t tests comparing average baseline MAIA-2 scores. We utilized stepwise regression models to further examine the potential association between prior exposure to OMT and MAIA-2. For variables that t tests had revealed a significant between-group difference (p<0.05), we added potential covariates to stepwise regression models one at a time, utilizing p=0.08 as the cutoff for inclusion in the final model and reported results with a beta coefficient and 95 % confidence interval (CI). We further investigated the potential association between MAIA-2 scales and exposure to OMT for the entire pooled sample with exposure to OMT as a continuous independent variable. Changes in the MAIA-2 scores pre-post OMT session were compared between subgroups by t tests.

We utilized t tests to examine pre-post changes in clinical outcomes (pain intensity, pain interference, patient’s global impression of change). We conducted clinical outcome tests for the entire sample and separately for OMT-naive vs. OMT-experienced and acute vs. chronic pain.

Recruitment, enrollment, and retention

Sixty-two consecutive potential participants were approached. Eight declined due to time constraints, thus 54 were assessed for eligibility. Among those 54 individuals, 12 were ineligible, 42 were eligible and enrolled, 36 of whom were included in the analysis. Reasons for exclusion from the analysis were: (1) the treatment team became unblinded to patients’ study enrollment status prior to or during the OMT session (n=5); and (2) a participant had shoulder surgery during the study period and thus was excluded on the basis that their pain scale was likely an outlier (n=1). We had 100 % retention of participants through the follow-up period, as shown in Figure 1 participant study flow diagram.

Figure 1:

Participant study flow diagram.

Participant characteristics

The mean age was 33 (±11.7, observed range 22–69) years old, 63.9 % (n=23) were female, and one participant gender-identified as “other” (Table 1). Meanwhile, 52.7 % (n=19) were OMT-naïve, and 47.2 % (n=17) were OMT-experienced. Participants with prior OMT exposure rated the type of touch at 4.25 (±1.55, observed range 0–7) on a scale of 0–10 (0=gentle, 5=mix of gentle and forceful, 10=forceful) for the mean response.

Pain duration was categorized as 41.7 % acute (<3 months) and 58.3 % chronic (>3 months). The mean baseline current pain intensity was 3.25 (±2.23, observed range 0–7) and 3.97 (±2.13, observed range 0–9) for the previous 7 days. The mean pain interference on 0–4 scale was 2.09 (±1.01).

Covariates (mind–body activities, non-OMT bodywork, physical and emotional trauma assessed on 0–10 scales) were similar between OMT-naive vs. OMT-experienced, and between participants with acute vs. chronic pain. Therefore, we did not adjust analyses by group for covariates and present our participant characteristics for the sample as a whole. Across the entire sample, mean prior exposure to mind–body activities and non-OMT bodywork scored 5.97 (±2.64) and 4.89 (±2.57), respectively. For prior trauma, mean scores were 4.00 (±3.37; mean age of occurrence at 17.7 [±9.73] years) for physical and 5.17 (±3.45) for emotional trauma (mean age of occurrence at 21.3 [±11.6] years).

Interoceptive bodily awareness

At baseline, the OMT-experienced group scored higher than the OMT-naive group on MAIA-2 scales “Not-Worrying” (3.11 vs. 2.41, p=0.002) and “Trusting” (4.02 vs. 3.31, p=0.028) (Figure 2a). Linear regression analysis of these MAIA scales by prior exposure to OMT as a continuous variable showed that 9 % of the variance of “Not-Worrying” (β=0.05; 95 % CI, −0.02 to 0.08) and 21 % of the variance for “Trusting” (β=0.04; 95 % CI, −0.01 to 0.09) was explained by the number of prior OMT sessions (Table 3). Associations between prior exposure to OMT by group and baseline MAIA scores were not modified by covariates (mind–body activities, non-OMT bodywork, physical and emotional trauma) in logistic regressions, and therefore analyses were not adjusted by covariates. MAIA scores did not significantly differ between the acute and chronic pain subgroups; however, patients with acute pain trended toward higher scores on the MAIA scale “Emotional Awareness” compared with chronic pain (3.92 vs. 3.48, p=0.078) (Table 2). There were no significant differences in MAIA scores at baseline compared to after the single OMT session or at any of the follow-up time points. Our first hypothesis was accepted partially in that the OMT-experience group scored higher on two of the eight scales. Our second hypothesis was not accepted in this study because we did not observe changes in MAIA scores following the single OMT session.

Figure 2:

(A) Mean baseline MAIA scores (with standard deviation) for scales with a significant difference between OMT experience groups (experienced vs. naïve; t tests). (B) Association of baseline MAIA scores (for scales with significant difference between experience groups) with the number of previous OMT sessions (as continuous variable from 0–20 sessions, >20 sessions=21 on scale). Pearson correlation coefficients: not-worrying: r=0.46; trusting: r=0.29.

Pain outcomes

In analyzing our sample as a whole, participants reported significant decreases in all pain outcomes: both current pain and average pain intensity over the previous 7 days, pain interference, and patient impression of change at all follow-up time points compared to pretreatment, with diminishing effects over time (Table 4, Figure 3).

Figure 3:

Pain outcomes for the entire sample.

Subgroup analysis (OMT-naive vs. OMT-experienced groups, acute vs. chronic pain groups) revealed that OMT-naive participants reported the greatest decrease in pain interference, compared to all other subgroups. Participants with acute pain experienced the greatest decrease in pain intensity compared to all other subgroups (Table 5).

Linear regression models for baseline MAIA scores and pain outcomes revealed that “Emotional Awareness” and “Body Listening” baseline scores were significantly related to change in pain interference at 1 week (β=−0.42; 95 % CI, −0.74 to −0.10, and β=−0.25; 95 % CI, −0.44 to −0.05, respectively), and “Noticing” and “Trusting” baseline scores were related to the change in participants’ impression of change at 3 weeks (β=0.10; 95 % CI, −0.11 to 2.00, and β=0.85; 95 % CI, 0.08 to 1.61, respectively) (Table 6). While there was no significant association between baseline MAIA scores and changes in pain intensity, we observed trends for both “Not Worrying” and “Emotional Awareness” baseline scores to be associated with changes in current pain at 1 week (p=0.065 and 0.056, respectively).

Limitations

This study was a small pilot study and was not powered for statistical significance, thus our statistical analyses may only suggest possible associations between data points. Because the study was conducted without a control group, causal inferences are not permitted. Our convenience sampling method limits the generalizability of our study. Additionally, given that there were differences in the MAIA scores between OMT exposure groups at baseline, this limits the power of comparing post-outcomes between the groups. In future studies with larger cohorts examining the relationship between OMT and MAIA, we recommend adjusting for prior OMT exposure.

In prior controlled OMT studies that found a positive correlation between OMT and interoception, participants were unable to distinguish the group to which they had been assigned. This suggested that the findings were not due to a placebo effect [42, 46]. Because it is impossible for practitioners to be blinded to the treatment in procedural studies, including OMT and surgery, and given that baseline MAIA scores may predict treatment responses [63], it is important to have at least a single-blind placebo control group to reduce bias. Given that our sample’s baseline pain levels were relatively low, we cannot infer that our findings would be consistent among individuals with higher baseline pain levels.

In this study, we did not track the physical examination findings of participants nor the specific techniques utilized in the OMT session, and it is known that physiologic responses to OMT and spinal manipulation are approach-specific and vary based on the technique administered, anatomic location of delivery, physical complaint, physical findings, presence of comorbidities, and the clinician’s and/or patient’s body type. While conducting an observational study on usual care, OMT is limited in its reproducibility due to the inherent variation between patient presentation as well as the practitioner-dependent approach to OMT, gathering this level of detail in future larger studies would enable more in-depth analysis of the potential relationships between OMT and IBA. Additionally, future studies should capture more comprehensive details of the patient’s chief complaint, comorbidities, and pain history (including onset, duration, location, characteristic, aggravating factors, relieving factors, timing, surgical history, interventional pain procedures, and the past or current use of any opioid or analgesic medications).