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Original Investigation
October 2018

Effect of Mobile Device–Supported Single-Patient Multi-crossover Trials on Treatment of Chronic Musculoskeletal Pain: A Randomized Clinical Trial

Author Affiliations
  • 1Department of Internal Medicine, University of California, Davis, Sacramento
  • 2Center for Health Care Policy and Research, University of California, Davis, Sacramento
  • 3Department of Biostatistics and Center for Evidence Synthesis in Health, Brown University School of Public Health, Providence, Rhode Island
  • 4Veterans Affairs Northern California Health Care System, Sacramento Medical Center, Mather
  • 5Department of Psychiatry, University of California, San Diego, San Diego
  • 6Betty Irene Moore School of Nursing, University of California, Davis, Sacramento
  • 7Division of General Internal Medicine & Health Services Research, Department of Medicine, University of California, Los Angeles, Los Angeles
  • 8Department of Psychiatry, Columbia University, New York, New York
  • 9Department of Clinical Informatics, University of California, Davis Medical Center, Sacramento
  • 10Department of Family and Community Medicine, University of California, Davis, Sacramento
  • 11Division of Environmental Health Sciences, University of Minnesota School of Public Health, Minneapolis
  • 12Open mHealth, New York, New York
  • 13Department of General Internal Medicine, University of California, San Francisco, San Francisco
JAMA Intern Med. 2018;178(10):1368-1377. doi:10.1001/jamainternmed.2018.3981
Key Points

Question  Does participation in an individually designed single-patient multi-crossover (n-of-1) trial improve pain-related or patient-engagement outcomes compared with usual care among patients with chronic musculoskeletal pain?

Findings  This randomized clinical trial found no significant difference in pain-related interference at 6-month follow-up between 108 patients randomized to an n-of-1 trial supported by a mobile app and 107 patients randomized to usual care. Medication-related shared decision making was significantly better in the n-of-1 group, and the n-of-1 participants were highly satisfied with the mobile app.

Meaning  In this study, n-of-1 trials supported by a mobile app were feasible and associated with a satisfactory user experience, but participation did not significantly improve pain interference.


Importance  Individually designed single-patient multi-crossover (n-of-1) trials can facilitate tailoring of treatments directed at various conditions, including chronic musculoskeletal pain (CMSP) but are potentially burdensome, which may limit uptake in research and practice.

Objectives  To determine whether patients randomized to participate in an n-of-1 trial supported by a mobile health (mHealth) app would experience less pain and improved global health, adherence, satisfaction, and shared decision making compared with patients assigned to usual care.

Design, Setting, and Participants  This randomized clinical trial compared participation in an individualized, mHealth-supported n-of-1 trial vs usual care. The participating 215 patients had CMSP for at least 6 weeks, had a smartphone or tablet with a data plan, were enrolled in northern California from July 2014 through July 2016, and were followed for up to 1 year by 48 clinicians in academic, community, Veterans Affairs, and military settings.

Interventions  Intervention patients met with their clinicians and used a desktop interface to select treatments and trial parameters for an n-of-1 trial comparing 2 pain-management regimens. The mHealth app provided reminders to take designated treatments on assigned days and to upload responses to daily questions on pain and treatment-associated adverse effects. Control patients received care as usual.

Main Outcomes and Measures  The primary outcome was change in the PROMIS (Patient-Reported Outcomes Measurement Information System) pain-related interference 8-item short-form scale (full scale range, 41-78) from baseline to 6 months. Secondary outcomes included patient-reported pain intensity, overall health, analgesic adherence, trust in clinician, satisfaction with care, medication-related shared decision making, and, for the n-of-1 group only, participant engagement and experience.

Results  Among 215 patients (108 randomized to the n-of-1 intervention and 107 to control), 102 (47%) were women, and the mean (SD) age was 55.5 (11.1) years. At the 6-month follow-up, pain interference was reduced in both groups, though there was no difference between the intervention and control groups (−1.36 points; 95% CI, −2.91 to 0.19 points; P = .09). There were no advantages in secondary outcomes for intervention patients vs control patients except for higher medication-related shared decision making at 6 months (between-group difference, 11.9 points; 95% CI, 2.6-21.2 points; P = .01). Among patients assigned to the n-of-1 group, 88% (n = 86) affirmed that the mHealth app could help people like them manage their pain.

Conclusions and Relevance  In this population of patients with CMSP, mHealth-supported n-of-1 trials were feasible and associated with a satisfactory user experience, but n-of-1 trial participation did not significantly improve pain interference at 6 months vs usual care.

Trial Registration  ClinicalTrials.gov identifier: NCT02116621

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