Chronic diabetic peripheral neuropathic pain: psychometric properties of pain and physical function outcome measures

Abstract

Background: Diabetic peripheral neuropathy (DPN) not only produces severe pain, tingling, and numbness sensation in the involved limbs, but also limits physical function due to loss of sensation. There are no recommended methods for clinical situations to measure these signs and symptoms. Studies with high methodological quality use the modified Brief Pain Inventory for Diabetic Peripheral Neuropathic pain (mBPI-DPN) scale and the short form Screening of Activity Limitations and Safety Awareness (sSALSA) scale for measuring these symptoms in DPN population. In order to capture a real change in the variables of interest, the psychometric properties of that measure should be within acceptable limits. As these two measures were not assessed for all of the psychometric properties, there was a need for further evaluation.

Methods: Data were collected (n = 38 patients) in a longitudinal cohort study. Test–retest reliability (0–4 weeks) and Responsiveness- Minimal Clinically Important Difference (MCID) (0–12 weeks) were calculated between two sessions. Convergent validity was assessed (between mBPI-DPN pain interference and sSALSA scale).

Results: Both measures demonstrated acceptable test–retest reliability (mBPI-DPN scale: ICC = 0.61, SEM = 12.92; the sSALSA scale: ICC = 0.81, SEM = 4.88) and convergent validity (Spearman’s correlation coefficient r = 0.62). The computational methods used in different methodologies to calculate MCID for the mBPI-DPN and the sSALSA scale were varied, hence the magnitude of derived MCID scores also varied.

Conclusions: Our study have provided evidence to add to the scientific basis surrounding the use of mBPI-DPN and sSALSA scales in DPN population, but standardization of these measures in a larger population is required

Keywords:

• Diabetic neuropathic pain
• physical functions
• reliability
• validity
• responsiveness

Trial registration:

• Australian New Zealand Clinical Trials Registry ACTRN12613000748718.

Acknowledgements

We thank all the participants for their participation in the study. The authors gratefully thank Dr Marina Moss (Clinical Research Administrator) for her guidance through the ethics process, assistance with recruitment, and booking of participants. Thanks to the School of Physiotherapy administration staff and Diabetes New Zealand for their help during the conduct of this research. The findings of the study have been submitted in the form of thesis for the award of PhD degree at the University of Otago, Dunedin, New Zealand. The results for this study have not been previously submitted or are under consideration at any other journal.

Disclosure statement

All authors declare that there exist no conflicts of interest associated with the current study, and corresponding author’s email address can be published.

Additional information

Funding

This study was supported by the Centre for Health, Activity, and Rehabilitation Research (CHARR), University of Otago, Dunedin, New Zealand, internal grant and the Mark Steptoe Memorial Trust, School of Physiotherapy; University of Otago, Dunedin, New Zealand for the research related costs. The sponsors had no role in the design or conduct of the study; data collection, analysis or interpretation of data; preparation or review of the manuscript.

Notes on contributors

Poonam Mehta

Dr. Poonam Mehta's doctoral research was in the area of Neuropathic pain and was completed in 2015; her thesis was entitled “Neuropathic pain: Outcome measures and their psychometric properties”. This study focused on identifying the reliable and valid outcome measures for diabetic neuropathic pain. Her current research interests are in the health and wellbeing of ageing people and through her current roles she is further developing her skills and passion for research in the area of ageing health and wellbeing.Professor David Baxter TD is currently Director for the New Zealand National Science Challenge for Ageing Well. David’s research expertise is in the fields of rehabilitation, low back pain, complementary and alternative medicine, as well as in laser medicine. His current projects include physical activity interventions (principally walking interventions) for health, photobiomodulation of delayed wound healing, and clinical effectiveness of acupuncture (including laser devices) as an alternative to needles in treatment of pai.

Leica Sarah Claydon

Dr Ramakrishnan Mani is a senior lecturer at the School of Physiotherapy, University of Otago. His research interests are Chronic pain mechanisms (central sensitisation, neuroplasticity, and psychosocial factors); life-course approach to predict MSK pain development and chronicity; pain education / curriculum; sedentary behaviour.

Ramakrishnan Mani

Dr Leica Claydon is a senior lecturer in Physiotherapy in the Allied and Public Health Department at Anglia Ruskin University. She is currently working in the fields of pain, neurological conditions and education. Her research interests are Systematic reviews (and meta-analysis), Non-pharmacological management of pain (particularly Neuropathic Pain) activity, and Education.

Paul Hendrick

Dr Paul Hendrick is a lecturer in the Division of Physiotherapy and Rehabilitation Sciences, and has worked in a range of clinical fields including musculoskeletal, sports rehabilitation and chronic pain management.

Chad Cook

Prof Chad Cook is a clinical researcher, physical therapist, and profession advocate with a history of clinical care excellence and service. His passions include refining and improving the patient examination process and validating tools used in day-to-day physical therapist practice.