Factors influencing adult and adolescent completion of treatment for late syphilis: a mixed methods systematic review.

Objective: To identify factors influencing the completion of a three-dose course of weekly intramuscular benzathine penicillin G injections by adults and adolescents with syphilis of unknown duration or late syphilis.

Methods: We searched medical literature databases for studies reporting on factors influencing treatment completion by patients with syphilis aged 10 years or older and studies involving health professionals administering syphilis treatment. Studies could use quantitative, qualitative or mixed methods approaches. We conducted a systematic review following the JBI Manual for Evidence Synthesis method.

Findings: We identified 24 eligible studies, of which 20 (83%) were published in 2010 or later, 19 (79%) focused on pregnant women, seven (29%) were conducted in Brazil, six (25%) in the United States of America and three (12%) in China. Health-care system-related factors influencing the noncompletion of treatment included the limited supply of, and limited access to, medication and inadequate follow-up systems. Other common factors were patients presenting late to antenatal services and social and economic factors, such as transportation barriers and a low educational level.

Conclusion: A comprehensive systems approach is needed to increase the treatment completion rate for syphilis of unknown duration and late syphilis. Health service interventions, such as improving patient management systems, should be supplemented by actions to address social inequalities and shortages in the supply of benzathine penicillin G. Research is needed to understand barriers to treatment completion in high-income countries and among priority groups, including Indigenous people and men who have sex with men.