Measuring the longitudinal HIV pre-exposure prophylaxis and condom usage pattern in men who have sex with men: short-call diary versus monthly survey

Abstract Background While a diary is ideal for recording daily sexual activity and drug taking, summarised survey is commonly used in real-world settings. This study aims to compare the robustness of short-recall diary with monthly survey on PrEP and condom use in men who have sex with men (MSM). Methods This forms part of an HIV PrEP implementation study involving adult MSM in Hong Kong. Over a one-year period, each participant completed both short-recall diary and monthly surveys retrospectively. Consistency between the two methods in measuring PrEP use pattern and condom use frequency, as well as compliance with survey completion were the primary outcomes. Kappa value was used to quantify consistency. Results Between Jan-2020 and June-2023, a total of 90,678 diary and 2022 monthly records from 287 MSM were collected, of which 51,359 and 1988 respective records from 268 MSM were used for comparison. Compliance with short-recall diary completion was significantly higher than that for monthly surveys (86% vs. 36%, P < 0.001). Compared to short-recall diary, monthly surveys reported significantly higher proportion of on-demand PrEP use (27% vs. 9%), inconsistent (52% vs. 43%) and consistent condom use (10% vs. 1%) ( P < 0.001). The Kappa value for condom use significantly decreased with the increased follow-up visits ( P = 0.022). MSM diagnosed with syphilis were more likely to achieve a Kappa value of 1 (aOR = 1.93, 95%CI = 1.03–3.62). Conclusions Compared to short-recall diary, monthly survey might over-estimate on-demand PrEP use due to complex 2-1-1 regimen. If resource is available, diary is a preferrable tool for measuring variables that require continuous monitoring.