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.
Agency for Public Health, Lazio Region, Rome, Italy. giorgirossi@asplazio.it
Paolo
P
Giorgi Rossi
Gennaro
G
Esposito
Silvia
S
Brezzi
Angela
A
Brachini
Patrizio
P
Raggi
Antonio
A
Federici
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*