Objective wearable measures and subjective questionnaires for predicting response to neurostimulation in people with chronic pain

BACKGROUND

Neurostimulation is an effective therapy for treating and management of refractory chronic pain. However, the complex nature of pain and infrequent in-clinic visits, determining subject's long-term response to the therapy remains difficult. Frequent measurement of pain in this population can help with early diagnosis, disease progression monitoring, and evaluating long-term therapeutic efficacy. This paper compares the utilization of the common subjective patient-reported outcomes with objective measures captured through a wearable device for predicting the response to neurostimulation therapy.

METHOD

Data is from the ongoing international prospective post-market REALITY clinical study, which collects long-term patient-reported outcomes from 557 subjects implanted by Spinal Cord Stimulator (SCS) or Dorsal Root Ganglia (DRG) neurostimulators. The REALITY sub-study was designed for collecting additional wearables data on a subset of 20 participants implanted with SCS devices for up to six months post implantation. We first implemented a combination of dimensionality reduction algorithms and correlation analyses to explore the mathematical relationships between objective wearable data and subjective patient-reported outcomes. We then developed machine learning models to predict therapy outcome based on the subject's response to the numerical rating scale (NRS) or patient global impression of change (PGIC).

RESULTS

Principal component analysis showed that psychological aspects of pain were associated with heart rate variability, while movement-related measures were strongly associated with patient-reported outcomes related to physical function and social role participation. Our machine learning models using objective wearable data predicted PGIC and NRS outcomes with high accuracy without subjective data. The prediction accuracy was higher for PGIC compared with the NRS using subjective-only measures primarily driven by the patient satisfaction feature. Similarly, the PGIC questions reflect an overall change since the study onset and could be a better predictor of long-term neurostimulation therapy outcome.

CONCLUSIONS

The significance of this study is to introduce a novel use of wearable data collected from a subset of patients to capture multi-dimensional aspects of pain and compare the prediction power with the subjective data from a larger data set. The discovery of pain digital biomarkers could result in a better understanding of the patient's response to therapy and their general well-being.

Comparing patient global impression of severity and patient global impression of change to evaluate test-retest reliability of depression, non-small cell lung cancer, and asthma measures

Purpose

Score reproducibility is an important measurement property of fit-for-purpose patient-reported outcome (PRO) measures. It is commonly assessed via test–retest reliability, and best evaluated with a stable participant sample, which can be challenging to identify in diseases with highly variable symptoms. To provide empirical evidence comparing the retrospective (patient global impression of change [PGIC]) and current state (patient global impression of severity [PGIS]) approaches to identifying a stable subgroup for test–retest analyses, 3 PRO Consortium working groups collected data using both items as anchor measures.

Methods

The PGIS was completed on Day 1 and Day 8 + 3 for the depression and non-small cell lung cancer (NSCLC) studies, and daily for the asthma study and compared between Day 3 and 10. The PGIC was completed on the final day in each study. Scores were compared using an intraclass correlation coefficient (ICC) for participants who reported “no change” between timepoints for each anchor.

Results

ICCs using the PGIS “no change” group were higher for depression (0.84 vs. 0.74), nighttime asthma (0.95 vs. 0.53) and daytime asthma (0.86 vs. 0.68) compared to the PGIC “no change” group. ICCs were similar for NSCLC (PGIS: 0.87; PGIC: 0.85).

Conclusion

When considering anchor measures to identify a stable subgroup for test–retest reliability analyses, current state anchors perform better than retrospective anchors. Researchers should carefully consider the type of anchor selected, the time period covered, and should ensure anchor content is consistent with the target measure concept, as well as inclusion of both current and retrospective anchor measures.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11136-022-03180-5.

Experiences of an outpatient infusion center with intravenous magnesium therapy for status migrainosus

OBJECTIVES

Exploratory study to investigate the effectiveness of intravenous magnesium as an abortive for status migrainosus in an outpatient infusion center, and characterize the patients who benefit from the therapy.

PATIENTS & METHODS

Retrospective analysis of 234 migraine patients who received IV magnesium as a headache abortive, at the headache clinic of University of Southern California. Additional intramuscular (IM) injections for nausea (prochlorperazine, odansetron, metoclopramide) or for refractory pain (ketorolac, dexamethasone, sumatriptan, dihydroergotamine), were administered as necessary. Immediately before and after treatment, self-reported pain levels were recorded using an 11-point numeric pain rating scale (0-10).

RESULTS

Our patient sample has a mean age of 44 years and was predominantly female (79%). 36 (19%) had migraine with aura. Overall, pain score decreased from 5.46±2.39 to 3.56 ± 2.75 (P < 0.001) after magnesium infusion. One hundred twenty-seven (54%) patients had clinically significant pain reduction, as defined by pain decrease ≥ 30%. One hundred and four patients (44%) received IV magnesium and did not require additional intramuscular (IM) medications for pain. In patients who did not receive additional IM medications for pain, pain score decreased from 4.76 ± 2.41 to 2.95 ± 2.70 (p < 0.001), and 61 out of 104 (59%) experienced ≥ 30% pain reduction. Patients with less severe pain tended to have a better response than patients with more severe pain, as patients with ≥30% pain reduction had a significantly lower pre-treatment pain score (p = 0.018).

CONCLUSION

For a subset of patients with status migrainosus, IV magnesium therapy results in clinically significant pain relief without the need for intramuscular pain medications. Therefore, IV magnesium may be useful as a cost-effective first-line parental therapy for status migrainosus, especially for patients who initially present with lower pain intensity.

Patients' and therapists' perception of change following physiotherapy in an orthopedic hospital's outpatient clinic

OBJECTIVE

The aims of this observational, prospective cohort study were to: assess the patients' and therapists' perception of change after physiotherapy in an orthopedic hospital's outpatient clinic; relate these retrospective assessments to a serial assessment of pain; and study the influence of patient characteristics on the perceived change.

METHODS

161 patients of the outpatient clinic participated. The main outcome measures were the patient global impression of change (PGIC) and the clinical global impression of change (CGIC) after physiotherapy. The visual analogue scale was used as serial assessment.

RESULTS

The PGIC indicated improvement in 128 patients (80%) and the CGIC in 117 patients (73%). The correlation between PGIC and CGIC was good (rS = 0.71, p < 0.001). The perceived change correlated little to baseline pain (PGIC: rS = 0.24, p = 0.004; CGIC: rS = 0.18, p = 0.024) and change in pain due to physiotherapy (PGIC: rS = -0.22, p = 0.004; CGIC: rS = -0.31, p < 0.001). The logistic regression model revealed a significant influence of the patients' education level and the number of problems on the PGIC and the CGIC.

CONCLUSIONS

The addition of at least one GPC scale might be valuable in evaluating the outcome in physical therapy, which requires little time and thus may be ideal for a clinical setting. Patients' and therapists' perception of change is significantly influenced by the patients' education level and the number of problems, which might be of relevance when choosing adequate treatment strategies.