Dual Intervention to Increase Chlamydia Retesting: A Randomized Controlled Trial in Three Populations

INTRODUCTION:Chlamydia retesting 3 months after treatment is recommended to detect reinfections, but retesting rates are typically low. The purpose of this study is to determine if the addition of a postal home collection kit to a short message service (SMS) reminder at 3 months increases the percentage of patients retested for chlamydia at 1-4 months, compared to SMS alone. DESIGN:In this unblinded randomized controlled trial, participants were randomized 1:1 to intervention (home arm) or control (clinic arm) status. SETTING/PARTICIPANTS:Participants included 200 each of women, heterosexual men, and men who have sex with men diagnosed and treated for chlamydia at sexual health services. INTERVENTION:Three months after chlamydia diagnosis, home arm participants received an SMS reminder and postal home collection kit (women, vaginal swab; heterosexual men, Copan UriSwab; men who have sex with men, UriSwab and rectal swab). MAIN OUTCOME MEASURES:The main outcome measures were the percentage of participants retested at 1-4 months after chlamydia diagnosis and the percentage in each arm with repeat positive tests, by risk group and overall, analyzed by intention to treat. Data were collected from 2011 to 2013 and analyzed in 2014. RESULTS:The percentage retested within 1-4 months of chlamydia diagnosis was significantly higher in home versus clinic arm participants among women (64% [66/103] vs 39% [38/97], p<0.001); heterosexual men (56% [57/101] vs 34% [34/99], p=0.002); men who have sex with men (62% [61/98] vs 44% [45/102], p=0.010); and overall (61% [184/302] vs 39% [117/298], p<0.001). The percentage in the home versus clinic arm with repeat positive tests was significantly higher among men who have sex with men (16% [16/98] vs 5% [5/102], p=0.021) and overall (10% [31/302] vs 4% [12/298], p=0.006). CONCLUSIONS:The addition of a postal home collection kit to routine SMS reminders resulted in substantial improvements in chlamydia retesting rates in all three risk groups and detection of more repeat positive tests, compared with SMS alone. Extending the intervention to other primary care settings with low retesting rates should be considered.