Participants were recruited consecutively from 1 March to 30 July 2022. During the study period, clients who visited the center were invited to participate. They were also encouraged to introduce their gay friends to come and join in this study. MSM in the contact list were also invited by phone. Additionally, recruitment information was also published via two social networking apps (WeChat and BLUED) and some settings where gay activities occur (gay bars/clubs/bathhouses). The study inclusion criteria were men aged ≥18 years, self-reported as having had oral or anal sex with another man in the past year, a negative HIV test result, and a resident of Guangxi. Individuals with mental disabilities were excluded. Four center MSM peer staff were hired and trained to facilitate the recruitment and interviews.

A structured questionnaire was used to collect information including demographic characteristics (age, ethnicity, occupation, education level, marital status, area of residence, and monthly income), sexual behaviors, sexualized drug use in the past year, HIV knowledge, HIV attitude and behavior, experience of using PrEP, willingness to use CAB-LA, and the maximum of willing to pay for CAB-LA. Knowledge of HIV was assessed by presenting participants with six questions/statements to answer: (1) AIDS is a serious infectious disease with high mortality. (2) AIDS needs lifelong treatment. (3) Can HIV be transmitted through sex? (4) MSM is the high-risk population of HIV infection. (5) List the ways that people can protect themselves from sexual transmission of HIV. (6) Correct condom use during sex can reduce the risk of HIV infection. The possible responses for item 5 were as follows: “Condom use,” “I don’t know,” or “Other.” Responses to the other five questions/statements were either “Yes” or “No.” All correct answers were considered “good knowledge of HIV” and otherwise considered “poor knowledge of HIV.” Willingness to use CAB-LA was assessed as follows: a brief introduction of CAB-LA was given to each participant, including the treatment regimen, its effectiveness, and side effects based on the results of clinical trials. Participants would also be given the opportunity to ask any questions with their concerns. After the introduction, the interviewer would ask the following question: “If CAB-LA is approved in China, and is available on the market with free of cost, would you use it?” Answers were measured on a 5-point Likert scale: 1 = definitely would, 2 = probably would, 3 = uncertain, 4 = probably would not, and 5 = definitely would not. Excluding those who answered “definitely would not,” participants were further asked the maximum amount that they were willing to pay per month (CNY) for CAB-LA if it was not free, which used an open question where the participants could fill in the price they prefer. All the participants were given a rapid HIV and syphilis screening, and those who tested positive were referred to the Nanning Center for Disease Control and Prevention for confirmation and counseling (if required).

Data management was performed using EpiData version 3.1 (EpiData Association, Odense, Denmark) with double-entry and verification. Data were analyzed using R version 4.1.2. (R Foundation for Statistical Computing, Vienna, Austria). The maximum amount of willing to pay per month was classified into <100, 100–199, 200–299, 300–399, 400–499, 500–599, and ≥600 CNY seven groups based on the data distribution. Unprotected sex behavior was defined as no or inconsistent condom use in the past month. Univariate and multivariate ordinal logistic regression analyses were performed to explore the associated factors of the maximum amount of willing to pay for CAB-LA presenting crude odds ratio (OR), adjusted OR, and 95% confidence interval (95% CI). Variables with a p-value less than 0.1 in the univariate analysis were included in the initial multivariate analysis. The statistical significance level was set as 0.05. The Cochran–Armitage trend test and PED were used to measure a change in the proportion/number of participants willing to pay to a change in price (the maximum amount of willing to pay per month). PED was measured successively at price decreased from 600 to 500, 400, 300, and 200 CNY per month using the following formula:

where

QN is the new quantity demanded after the maximum amount of willing to pay decreased 100 CNY per month.

QI is the initial quantity demanded before the maximum amount of willing to pay decreased 100 CNY per month.

PN is the new maximum amount of willing to pay per month.

PI is the initial maximum amount of willing to pay per month.

If PED>1: which means the change in price leads to an even bigger change in demand, the product is very responsive to a change in price. If PED<1, which means the product is relatively unresponsive to a change in price. When a unitary elastic good has a change in demand which is equal to the change in price, PED = 1.

To our knowledge, this is the first study to assess the maximum amount of willing to pay and PED for CAB-LA among MSM in China after CAB-LA has been approved for use in the United States. Our study showed that the median of the maximum amount of willing to pay was 200 CNY per month (interquartile: 100–500 CNY) and majority of participants (84.2%) willing to pay less than 600 CNY per month for CAB-LA. Younger age, higher education level, having a high monthly income, being bisexual/unsure sexual orientation, and experience of using PrEP were positively associated with the maximum amount of willing to pay for CAB-LA. When the price was decreased from 600 to 500, 400, 300, 200, and 100 CNY per month, PED was decreased gradually.

The maximum amount of willing to pay for CAB-LA was low in Guangxi, China. Associated factors included age, education level, monthly income, self-reported sexual orientation, and experience of using PrEP. PED of CAB-LA is relatively elastic. The waived patent protection should be considered for the wide promotion of CAB-LA, and the health education should be strengthened to improve the recognition of CAB-LA.

The original contributions presented in the study are included in the article/Supplementary Material; further inquiries can be directed to the corresponding author.

The studies involving humans were approved by the Ethics Committee of Guangxi Medical University. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.

SC: writing–review and editing, writing–original draft, and investigation. YR: writing–original draft and writing–review and editing. LL: writing–review and editing and investigation. HP: writing–review and editing and investigation. YJ: writing–review and editing and investigation. TH: writing–review and editing and investigation. YW: writing–review and editing and investigation. LQ: writing–review and editing and investigation. XD: writing–review and editing and investigation. YL: writing–review and editing and investigation. JL: writing–review and editing and investigation. YX: writing–original draft, and writing–review and editing.

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. The research was supported by the Ministry of Science and Technology of China (2022YFC2305205; 2022YFC2305201), National Natural Science Foundation of China (11971479; 82260670), Guangxi Bagui Honor Scholarship, and Chinese State Key Laboratory of Infectious Disease Prevention and Control.

The authors thank all staff at the Nanning gay-friendly health consulting service center for their help in the participants’ recruitment and for conducting face-to-face interview.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors, and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.