Osteoarthritis VAS Pain Scores Correlate With WOMAC Weight-Bearing Pain Scores

The 24-hour, single-question VAS pain scale correlated most strongly with the pain subscale of the WOMAC among patients with osteoarthritis.

Visual analog scale (VAS) pain scores were found to correlate most strongly with Western Ontario and McMaster University Arthritis Index (WOMAC) weight-bearing scores among patients with osteoarthritis, according to the results of study published in Pain Reports.

Investigators from NBCD A/S, a biotechnology contract research organization in Denmark, sourced data for this study from 2 phase 3 clinical trials (ClinicalTrials.gov Identifiers: NCT00486434 and NCT00704847) that investigated the efficacy and safety of oral salmon calcitonin in patients with osteoarthritis. This cross-sectional study evaluated the correlation between VAS and WOMAC pain domains.

The mean age of study participants (N=2093) was 64.4 (range, 6.8) years, 34.8% were men, mean body mass index (BMI) was 28.9 (SD, 4.9) kg/m2, and 2.5% had Kellgren-Lawrence (KL) radiologic grade 4 osteoarthritis severity in the nontarget knee.

The average 100-point VAS pain score was 50.83 (standard deviation [SD], 20.46) points, and the average 100-point WOMAC pain score was 48.37 (SD, 14.67) points.

Our results suggest that VAS pain scale correlated more accurately with the weight-bearing construct of WOMAC pain subscale as compared with the WOMAC pain non-weight-bearing construct.

The 2 pain scores were found to correlate (r, 0.67; P <.0001). When stratifying the WOMAC score into weight-bearing pain and nonweight-bearing pain components, a stronger correlation with VAS scores were observed for weight-bearing scores (r, 0.68; P <.0001) than for nonweight-bearing scores (r, 0.55; P <.0001).

Stratified by quintiles of VAS and the 5 components of the WOMAC, the WOMAC walking score correlated with all but the second quintile VAS (r range, 0.11-0.31; all P ≤.05), the WOMAC stairs score correlated with all VAS quintiles (r range, 0.10-0.34; all P ≤.02), the WOMAC nocturnal scores correlated with the first (r, 0.18; P <.001) and fifth (r, 0.28; P <.001) VAS quintiles, the WOMAC rest scores correlated with all but the third and fourth VAS quintiles (r range, 0.07-0.28; all P ≤.003), and the WOMAC standing score correlated with the first (r, 0.33; P <.001) and second (r, 0.06; P <.001) VAS quintiles.

The discordance in VAS and WOMAC scores was associated with the KL grade of the nontarget knee (P =.002), in which the greater divergence in VAS and WOMAC scores was found to be associated with greater KL grade (P =.02). The relationship with KL grade was even larger with the discordance between VAS and weight-bearing WOMAC scores (P <.0001).

This study may have been limited by the majority of patients experiencing mild to moderate disease.

Study authors concluded, “The 24-hour single-question VAS pain scale and the pain subscale of WOMAC were moderately correlated. Our results suggest that VAS pain scale correlated more accurately with the weight-bearing construct of WOMAC pain subscale as compared with the WOMAC pain nonweight-bearing construct. Agreement between VAS pain and WOMAC pain was best in the extreme ranges of the scale.”

Disclosure: Multiple study authors are employed by or are shareholders of NBCD A/S. Please see the original reference for a full list of authors’ disclosures.

This article originally appeared on Clinical Pain Advisor

References:

Bjerre-Bastos JJ, Miller CP, Li Y, Andersen JR, Karsdal M, Bihlet AR. Associations between single-question Visual Analogue Scale pain score and weight-bearing and nonweight-bearing domains of Western Ontario and McMaster Universities Arthritis Index pain: data from 2 phase 3 clinical trials. Pain Rep. 2022;7(5):1017. doi:10.1097/PR9.0000000000001017