Estimation of Pap-test coverage in an area with an organised screening program: challenges for survey methods.
BACKGROUND
The cytological screening programme of Viterbo has completed the second round of invitations to the entire target population (age 25-64). From a public health perspective, it is important to know the Pap-test coverage rate and the use of opportunistic screening. The most commonly used study design is the survey, but the validity of self-reports and the assumptions made about non respondents are often questioned.


METHODS
From the target population, 940 women were sampled, and responded to a telephone interview about Pap-test utilisation. The answers were compared with the screening program registry; comparing the dates of Pap-tests reported by both sources. Sensitivity analyses were performed for coverage over a 36-month period, according to various assumptions regarding non respondents.


RESULTS
The response rate was 68%. The coverage over 36 months was 86.4% if we assume that non respondents had the same coverage as respondents, 66% if we assume they were not covered at all, and 74.6% if we adjust for screening compliance in the non respondents. The sensitivity and specificity of the question, "have you ever had a Pap test with the screening programme" were 84.5% and 82.2% respectively. The test dates reported in the interview tended to be more recent than those reported in the registry, but 68% were within 12 months of each other.


CONCLUSIONS
Surveys are useful tools to understand the effectiveness of a screening programme and women's self-report was sufficiently reliable in our setting, but the coverage estimates were strongly influenced by the assumptions we made regarding non respondents.
Giorgi Rossi
Paolo
P
Agency for Public Health, Lazio Region, Rome, Italy. giorgirossi@asplazio.it
Esposito
Gennaro
G
Brezzi
Silvia
S
Brachini
Angela
A
Raggi
Patrizio
P
Federici
Antonio
A
D000328:Adult; D003159:Community-Institutional Relations; D003430:Cross-Sectional Studies; D005260:Female; D019538:Health Care Surveys / Q000379:methods*; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007407:Interviews as Topic; D007558:Italy; D008403:Mass Screening / Q000458:organization & administration* / Q000706:statistics & numerical data; D011939:Mental Recall; D008875:Middle Aged; D010349:Patient Compliance / Q000523:psychology / Q000706:statistics & numerical data*; D015397:Program Evaluation; D012042:Registries; D017010:Reminder Systems; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000517:prevention & control; D014626:Vaginal Smears / Q000706:statistics & numerical data*