The Dutch language version of the Pain Disability Index (PDI-DLV): psychometric properties in breast cancer patients

ABSTRACT

Background

Pain after breast cancer surgery is a common and disabling problem. A reliable and valid questionnaire to assess pain-related disability is the Pain Disability Index (0–70). However, properties of the Dutch version (PDI-DLV) have never been investigated in this population.

Objective

To assess psychometric properties of the PDI-DLV after breast cancer surgery.

Methods

For reliability, relative and absolute reliability were calculated with a one-week test–retest interval, as well as internal consistency. Moreover, content and construct validity were examined to evaluate validity.

Results

One hundred twenty-three women were included. Relative reliability was good (intraclass correlation coefficient = 0.80). Standard error of measurement and minimal detectable change (absolute reliability) were 5.57 and 15.45 points, respectively. The mean difference between two measurements was −1.98 points, with 95% limits of agreement equal to 13.19 and −17.15. The within-subjects coefficient of variation was 59%. Internal consistency was confirmed (α = 0.87). The PDI-DLV was scored as understandable and complete (content validity). Construct validity was supported by confirmation of more than 75% of the tested hypotheses and of the one-factor model.

Conclusion

The PDI-DLV is a valid questionnaire to assess pain-related disability 1 year after breast cancer surgery. Although absolute reliability is disputable, its good relative reliability allows evaluating changes between subjects.

KEYWORDS:

• Pain-related disability
• pain disability index
• breast cancer
• reliability
• validity

Acknowledgments

We would like to express our appreciation to Steffen Fieuws from the Leuven Biostatistics and Statistical Bioinformatics Centre (L-BioStat) for his valuable advice on statistical analyses and interpretation of the data. The research team is also very grateful for the efforts and contribution of the participants, who made this research possible. This study was supported by the Research Foundation Flanders (Applied Biomedical Research) under Grant T005117N.

Disclosure statement

The funding source had no role in study design, data collection, data analysis, data interpretation or writing of the report. Within the last 3 years of beginning the work, Professor Bart Morlion had the following financial activities outside the submitted work: Pfizer, Gruenenthal, Kyowa-Kirin, GSK, Reckit and Benckiser and Shionogi. All other authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript

Additional information

Funding

This work was supported by the Research Foundation Flanders (Applied Biomedical Research) under Grant T005117N.