Consequences of current patterns of Pap smear and colposcopy use.

OBJECTIVES - To describe age specific frequencies of Pap smear and colposcopy use in the Australian Capital Territory (ACT) and to estimate the cumulative effects of current patterns of use. SETTING - Frequencies of Pap smear and colposcopy use were estimated for the financial year from 1 July 1989 to 30 June 1990. Eligible women were between the ages of 15 and 74, living in the ACT. METHODS - Data collected from a 10% sample of subjects enrolled with Medicare and from the only public pathology laboratory in the ACT were used to estimate age specific frequencies. The expected number of deaths from cervical cancer in the ACT in the absence of a screening programme was estimated by applying Australian age specific mortality rates for cervical cancer between 1960 and 1964 to the 1989 ACT population. A life table approach was used to simulate the cumulative risk of colposcopy - given current age specific rates - on a hypothetical cohort of 1000, 15 year old women. RESULTS - Forty four per cent (95% confidence interval (CI) 42.9 to 44.9) of women had a Pap smear and 2.5% had colposcopy (95% CI 2.4 to 2.6). Two and a half percent of 15 to 24 year old women had colposcopy (95% CI 1.9 to 3.1). The ratio of women having Pap smears to women having colposcopy was 17-8:1 (95% CI 17.7 to 17.9). An estimated 247 women had colposcopy for every cervical cancer death; in the 15 to 24 year old age group this ratio was 47900:1. A 15 year old woman exposed to current rates of colposcopy (adjusted for hysterectomy) has a 76.8% chance of having a colposcopy during her life time. CONCLUSIONS - Many more women will have colposcopy than will develop cervical cancer, which undermines the cost effectiveness of Australia's cervical cancer screening programme.