The numerical rating scale is the preferred patient-reported outcome measure for people with rheumatoid arthritis (RA), according to study results published in Clinical Rheumatology.
Compared with other patient-reported outcome measures, the numerical rating scale was more reliable for measuring pain and experienced disease activity. Patients favored the numerical rating scale over other patient-reported outcome measures.
Researchers assessed the construct validity and reproducibility of 4 types of patient-reported outcome measures: numerical rating scale, visual analog scale, verbal rating scale, and Likert scale. They also measured patient preference.
Participants with stable RA and no change in pain medication or steroid medication completed questionnaires directly following an outpatient visit and 5 days later (n=211). The questionnaire measured the validity of the patient-reported outcome measures in 4 domains: pain, fatigue, experienced disease activity, and general well-being.
The researchers calculated Pearson correlation coefficients using the Disease Activity Score-3 to assess construct validity. They calculated intraclass correlation coefficients to assess reproducibility.
The researchers did not find any differences in construct validity among the different patient-reported outcome measures.
The visual analog scale and the numerical rating scale scored better in the reproducibility aspect of both pain and experienced disease activity compared with the verbal rating scale and Likert scale (P <.05). The researchers did not find any differences between the visual analog scale and the numerical rating scale.
Participants most often selected the numerical rating scale as their preferred measurement method in every situation (ranging from 44.3% to 45.8%) with the visual analog scale consistently in second place (ranging from 20.8% to 24.5%). Depending on the domain, third and fourth place switched between the verbal rating scale and the Likert scale.
“Other studies have shown the practicality of the numerical rating scale over the visual analog scale; therefore, we think that the numerical rating scale is the preferred scale type for the different patient-reported outcome measures,” the researchers wrote.
Renskers L, van Uden RJJC, Huis AMP, Rongen SAA, Teerenstra S, van Riel PLCM. Comparison of the construct validity and reproducibility of four difference types of patient-reported outcome measures (PROMs) in patients with rheumatoid arthritis [published online September 12, 2018]. Clin Rheumatol. doi:10.1007/s10067-018-4285-x