Objective: To estimate the regression, persistence, and progression of untreated cervical intraepithelial neoplasia grade 2 (CIN2) lesions managed conservatively as well as compliance with follow-up protocols.
Design: Systematic review and meta-analysis.
Data sources: Medline, Embase, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) from 1 January 1973 to 20 August 2016.
Eligibility criteria: Studies reporting on outcomes of histologically confirmed CIN2 in non-pregnant women, managed conservatively for three or more months.
Data synthesis: Two reviewers extracted data and assessed risk of bias. Random effects model was used to calculate pooled proportions for each outcome, and heterogeneity was assessed using I2 statistics.
Main outcome measures: Rates of regression, persistence, or progression of CIN2 and default rates at different follow-up time points (3, 6, 12, 24, 36, and 60 months).
Results: 36 studies that included 3160 women were identified (seven randomised trials, 16 prospective cohorts, and 13 retrospective cohorts; 50% of the studies were at low risk of bias). At 24 months, the pooled rates were 50% (11 studies, 819/1470 women, 95% confidence interval 43% to 57%; I2=77%) for regression, 32% (eight studies, 334/1257 women, 23% to 42%; I2=82%) for persistence, and 18% (nine studies, 282/1445 women, 11% to 27%; I2=90%) for progression. In a subgroup analysis including 1069 women aged less than 30 years, the rates were 60% (four studies, 638/1069 women, 57% to 63%; I2=0%), 23% (two studies, 226/938 women, 20% to 26%; I2=97%), and 11% (three studies, 163/1033 women, 5% to 19%; I2=67%), respectively. The rate of non-compliance (at six to 24 months of follow-up) in prospective studies was around 10%.
Conclusions: Most CIN2 lesions, particularly in young women (<30 years), regress spontaneously. Active surveillance, rather than immediate intervention, is therefore justified, especially among young women who are likely to adhere to monitoring.
Systematic review registration: PROSPERO 2014: CRD42014014406.
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