Inhibitors and facilitators of willingness to participate (WTP) in an HIV vaccine trial: construction and initial validation of the Inhibitors and Facilitators of Willingness to Participate Scale (WPS) among women at risk for HIV infection

Abstract

A psychometric scale assessing inhibitors and facilitators of willingness to participate (WTP) in an HIV vaccine trial has not yet been developed. This study aimed to construct and derive the exploratory factor structure of such a scale. The 35-item Inhibitors and Facilitators of Willingness to Participate Scale (WPS) was developed and administered to a convenience sample of 264 Black females between the ages of 16 and 49 years living in an urban-informal settlement near Cape Town. The subscales of the WPS demonstrated good internal consistency with Cronbach's alpha coefficients ranging between 0.69 and 0.82. A principal components exploratory factor analysis revealed the presence of five latent factors. The factors, which accounted for 45.93% of the variance in WTP, were (1) personal costs, (2) safety and convenience, (3) stigmatisation, (4) personal gains and (5) social approval and trust. Against the backdrop of the study limitations, these results provide initial support for the reliability and construct validity of the WPS among the most eligible trial participants in the Western Cape of South Africa.

Keywords:

• Inhibitors and Facilitators of Willingness to Participate Scale (WPS)
• HIV vaccine trial
• South Africa

Acknowledgements

We thank the Desmond Tutu HIV Centre (DTHC) in Cape Town, South Africa, for providing access to participants. We also thank the South African National Research Foundation (NRF) for funding for this study. The views expressed in this article, and the conclusions reached, are those of the authors alone and not those of any other person or organisation.

Notes

1. An urban-informal settlement refers to a cluster of improvised dwellings made from scrap materials positioned on the periphery of a city.

2. Variances explained and eigenvalues refer to the rotated sum of squared loadings (initial solutions are not shown here).