Table 1. Characteristics of the populations included in the selected studies.

Authors	Lytwyn et al.,17 2000*	ALTS Group,7 2003†	Andersson et al.,18 2005
Country	Canada	United States	Sweden
Recruitment place	52 community-based family practices and one university student health clinic in Ontario	General, gynecological or family planning clinics in Alabama, Oklahoma, Pennsylvania and Washington	Population-based screening in Stockholm
Recruitment dates	November 1995 - October 1998	January 1997 - December 1998	NI
Recruitment type	Consecutive	Consecutive	Consecutive
Inclusion criteria	- Initial cytological findings of ASCUS or LSIL - Between 16 and 50 years old	- Initial cytological findings of ASCUS or LSIL up to six before recruitment - ³ 18 years old - Capable of providing consent and probably participate throughout the duration of the study	- Initial cytological findings of ASCUS or LSIL
Exclusion criteria	- Likelihood of non-adherence to follow-up - Pregnancy - Absent cervix - Previous diagnoses of high-grade CIN , AGC-US, glandular dysplasia or cervical cancer - Previous destructive cervical treatment - Vaginal or vulvar neoplasia - Followed with colposcopy at the time of recruitment - Immunosuppression - Uterine body or adnexal surgery required	- Previous hysterectomy - Previous destructive or excisional cervical treatment - Pregnancy	NI
Sample size (at time of initial cytological finding of LSIL)	69	1572	125
Age	Average: 30 years old < 35 years old: 58 (84%) ³ 35 years old: 11 (16%)	Average: 25 years old < 35 years old: 1437 (91%) ³ 35 years old: 135 (9%)	Average: 34 years old < 35 years old: NI ³ 35 years old: NI

^*Some data obtained from the author; ^†Data pertaining demographic characteristics were obtained from Schiffman & Adrianza, 2000²¹; NI = Not informed; ASCUS = Atypical Squamous Cells of Undetermined Significance; LSIL = Low Grade Squamous Intraepithelial Lesions; CIN = Cervical intraepithelial neoplasia; AGC-US = Atypical Glandular Cells of Undetermined Significance.