MENSTRUAL PAIN ASSESSMENT: COMPARING VERBAL RATING SCALE (VRS) WITH NUMERICAL RATING SCALES (NRS) AS PAIN MEASUREMENT TOOLS

Abstract

Background: Management of pain is optimized if the pain is assessed with the appropriate measuring tool. Verbal rating scale (VRS) and numerical rating scale (NRS) are pain assessment tools. This study was aimed at determining if there is an agreement between VRS and NRS in menstrual pain assessment and the cutoff point of VRS categories on the NRS. Methods: A semi-structure questionnaire was used to collect data from a cross sectional study involving 236 female undergraduate students of the School of Medicine and Health Sciences of the University for Development Studies, Tamale, Ghana. GraphPad Prism 5.01 and SPSS 21 statistical tools were used to analyze the data in this study. From a receiver operating characteristic (ROC) curve, the cut-off points of VRS categories on NRS were determined. Results: There was a positive, strong and significant correlation between the NRS - 10 and the VRS - 3 pain assessment instruments (Spearman’s rho = 0.81; 95% CI: 0.76 - 0.85; p-value < 0.0001). Agreement between VRS and NRS (kappa = 0.69) was good. The cut-off points for the VRS pain intensity categories of mild, moderate and severe on the NRS were 1 to 3, 4 to 6 and 7 to 10 respectively. Socio-demographic characteristics had no influence on the ability to place VRS category within the cut-off point ranges on the NRS except course of study with medical students scoring best (95.2% vrs 66.7 - 82.1%; χ2 = 10.1; df = 4; p value = 0.0387). Area under ROC curve scores were close to 1 (0.871, 0.9833, 0.9935; p < 0.0001) which showed that VRS and NRS exhibited a significant discriminatory capability in menstrual pain assessment. Conclusion: High correlation and discriminatory capability exist between VRS and NRS as tools for the measurement of menstrual pain. A kappa coefficient of 0.69 shows that the agreement between VRS and NRS is good hence both can be used for pain measurement. The cut-off points for the VRS pain intensity categories of mild, moderate and severe on the NRS were 1 to 3, 4 to 6 and 7 to 10 respectively.