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Interobserver reproducibility of the assessment of severity of complaints, grip strength, and pressure pain threshold in patients with lateral epicondylitis,☆☆,,★★,,♢♢

https://doi.org/10.1053/apmr.2002.33728Get rights and content

Abstract

Smidt N, van der Windt DA, Assendelft WJ, Mourits AJ, Devillé WL, de Winter AF, Bouter LM. Interobserver reproducibility of the assessment of severity of complaints, grip strength, and pressure pain threshold in patients with lateral epicondylitis. Arch Phys Med Rehabil 2002;83:1145-50. Objective: To evaluate the interobserver reproducibility of the assessment of severity of complaints, grip strength, and pressure pain threshold in patients with lateral epicondylitis in primary care. Design: Two physiotherapists assessed independently, and in randomized order, the severity of complaints scored on an 11-point numeric rating scale, pain-free grip strength, maximum grip strength, and pressure pain threshold. Setting: Primary care center in the Netherlands. Participants: Fifty patients were assessed by both physiotherapists. Interventions: Not applicable. Main Outcome Measures: Intraclass correlation coefficients (ICCs) and 95% confidence intervals (CIs) were calculated to assess interobserver reliability. The Bland and Altman method was used to assess interobserver agreement, which included calculation of the mean difference between the observers (d), the 95% CI for d, the standard deviation of the differences, and the 95% limits of agreement. Finally, the smallest detectable difference (SDD) was calculated. Results: The ICC for the severity of complaints was.90. The ICCs for the pain-free grip strength and maximum grip strength were.97 and.98, respectively. The pressure pain threshold showed a lower reliability (ICC=.77). The interobserver agreement for all outcome measures was good, but systematic differences in assessment between the physiotherapists were found for the maximum grip strength and pressure pain threshold. For pressure pain threshold, the SDD was clearly larger than the predefined acceptable difference of 10% of the total range of measurement. Conclusions: The interobserver reliability of severity of complaints and grip strength was excellent, whereas the pressure pain threshold showed unsatisfactory reliability. Grip strength and overall assessment of the severity of complaints are useful and reliable measures for the assessment of lateral epicondylitis. Pain-free grip strength, in particular, is relatively easy to perform and has been shown to be associated with other measures of functional disability in patients with lateral epicondylitis. We, therefore, recommend the use of pain-free grip strength in both research and clinical practice. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Section snippets

Patients

The participants of the reproducibility study were recruited from the study population of an RCT, comparing the effectiveness of corticosteroid injections, physiotherapy, and a wait-and-see policy for lateral epicondylitis.19 Patients were eligible for participation in the RCT if they had pain at the lateral side of the elbow, which increased with pressure on the lateral epicondyl and during resisted dorsiflexion of the wrist. Other inclusion criteria were elbow complaints ≥6 weeks, age between

Patients

The 50 participants of the reproducibility study were enrolled between July 1998 and January 1999. The mean age ± SD of the 50 patients was 47±11 years, and 40% of the patients were women (table 1).

. Main characteristics of the participants

Empty CellParticipants (N=50)
Female (%)20 (40)
Mean age (SD) in years47 (11)
Dominant side affected (%)35 (70)
Elbow disability (median, IQR)*5.5 (1.5–13.3)
Pain during the day (median, IQR)1 (0–4)
* Modified Pain Free Function Questionnaire: scores range from 0 to 40, with

Discussion

This study investigated the interobserver reproducibility of severity of complaints, grip strength, and pressure pain threshold in 50 patients with lateral epicondylitis. The results showed excellent reliability for the severity of complaints, pain-free grip strength, and maximum grip strength (ICC≥.90). The pressure pain threshold was clearly less reliable (ICC range,.72–.77). Systematic differences (bias) between the physiotherapists were found for the assessment of maximum grip strength and

Conclusion

Interobserver reproducibility for all outcome measures, except for pressure pain threshold, showed excellent results. An overall assessment of severity of symptoms by a trained physiotherapist showed good agreement and reliability and is a relevant measure in day-to-day clinical care. Some interobserver variation should be taken into account, particularly when examiners have different backgrounds and training. Pain-free grip strength showed high reliability and agreement, is relatively easy to

Acknowledgements

We thank Samyra Keus for performing the assessments.

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    Supported by the Netherlands Organization for Scientific Research and the Health Insurance Council's Fund for Investigative Medicine.

    ☆☆

    Reprint requests to Nynke Smidt, PhD, Institute for Research in Extramural Medicine, VU University Medical Center, Van der Boechorststr 7, 1081 BT Amsterdam, The Netherlands, e-mail: [email protected].

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.

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