Open Access Open Badges Research article

Assessment of the face validity of two pain scales in Kenya: a validation study using cognitive interviewing

Kristin TL Huang12, Claudio Owino135, Rachel C Vreeman14, Mildred Hagembe15, Festus Njuguna15, R Matthew Strother16 and Gregory P Gramelspacher16*

Author affiliations

1 USAID - Academic Model Providing Access to Healthcare (AMPATH), P.O. Box 4806, Eldoret, Kenya

2 Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts, 02115, USA

3 Moi University School of Medicine, P.O. Box 4606, 030100, Eldoret, Kenya

4 Department of Pediatrics, Indiana University School of Medicine, 410 W. 10th Street, HITS 1000, Indianapolis, Indiana, 46202, USA

5 Moi Teaching and Referral Hospital, Nandi Road, P.O. Box 3, 30100, Eldoret, Kenya

6 Department of Medicine, Indiana University School of Medicine, 545 Barnhill Drive, E317, Indianapolis, Indiana, 46202, USA

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Citation and License

BMC Palliative Care 2012, 11:5  doi:10.1186/1472-684X-11-5

Published: 18 April 2012



Patients in sub-Saharan Africa commonly experience pain, which often is un-assessed and undertreated. One hindrance to routine pain assessment in these settings is the lack of a single-item pain rating scale validated for the particular context. The goal of this study was to examine the face validity and cultural acceptability of two single-item pain scales, the Numerical Rating Scale (NRS) and the Faces Pain Scale-Revised (FPS-R), in a population of patients on the medical, surgical, and pediatric wards of Moi Teaching and Referral Hospital in Kenya.


Swahili versions of the NRS and FPS-R were developed by standard translation and back-translation. Cognitive interviews were performed with 15 patients at Moi Teaching and Referral Hospital in Eldoret, Kenya. Interview transcripts were analyzed on a question-by-question basis to identify major themes revealed through the cognitive interviewing process and to uncover any significant problems participants encountered with understanding and using the pain scales.


Cognitive interview analysis demonstrated that participants had good comprehension of both the NRS and the FPS-R and showed rational decision-making processes in choosing their responses. Participants felt that both scales were easy to use. The FPS-R was preferred almost unanimously to the NRS.


The face validity and acceptability of the Swahili versions of the NRS and FPS-R has been demonstrated for use in Kenyan patients. The broader application of these scales should be evaluated and may benefit patients who currently suffer from pain.