Assessing the effectiveness of a screening campaign: who is missed by 80% cervical screening coverage?

A case-control study was conducted to assess the effectiveness of a regional call programme in reaching women at risk of cervical cancer. Home interviews were conducted with a random sample of 614 women aged 20-64 who were identified from a computerized register as either having had a smear test within the previous 3 years or not having an up-to-date smear history. Unscreened women fell principally into two age cohorts: under 35 years and over 50 years. A small social class differential was found to persist following the campaign. Overall, unscreened women were not at epidemiologically higher risk than the screened population. Thirty-five per cent of unscreened women reported never having had sexual intercourse compared to 3% of screened women: 17% of the unscreened and 38% of screened women reported two or more lifetime sexual partners. No difference was observed between screened and unscreened women in the frequency of current cigarette smoking (37% unscreened, 38% screened). Cigarette smoking was, however, associated with social class (31% classes 1 or 2 compared with 50% classes 4 and 5). Level of practical difficulties did not differentiate those who attended from those who did not, suggesting that recent changes to delivery or screening services have been effective in ensuring equity of access. Non-attenders and lower class women held more negative attitudes towards the test procedure and were less likely to believe that they were at risk of cervical cancer. Perceived personal risk was not associated with cigarette smoking, suggesting that further attention might be given to this factor in educational campaigns.