Systematic selection of screening participants by risk score in a Chlamydia screening programme is feasible and effective.
OBJECTIVE
Systematic screening for Chlamydia trachomatis by individual invitation can be optimised by filtering participants on risk profile, excluding people at no or low risk. The authors investigated this technique in a large-scale chlamydia screening programme in The Netherlands in one rural region where relatively low prevalence was expected (<2%).


METHODS
Invitees were alerted by personal letter to log in to http://www.chlamydiatest.nl and fill in an 8-item questionnaire. Only invitees with sufficient score could proceed to request a test kit. The authors investigated the effect of selection on participation, positivity and acceptability in three screening rounds and on the number needed to invite and the number needed to screen.


RESULTS
The selection led to exclusion of 36% of potential participants and a positivity rate of 4.8% among participants, achieving similar number needed to screen values in the rural and urban areas. Higher scores were clearly related to higher positivity rates. Persons who were excluded from participation did not have a lower response in the next round. The acceptability study revealed disappointment about exclusion of 30% of excluded participants but most approved of the screening set-up.


CONCLUSIONS
Systematic selection of screening participants by risk score is feasible and successful in realising higher positivity rates. A somewhat stricter selection could be applied in the rural and urban areas of the screening programme. Multiple-item selection with a cut-off total score may work better than, more commonly used, selection by single criteria, especially in low-risk populations. Acceptability of selection is high but could still be improved by better communication on expectations.
Epidemiology and Surveillance Unit, Centre for Infectious Disease Control, National Institute of Public Health and the Environment, P.O. Box 1 (nr 75), BA 3720, The Netherlands. ingrid.van.den.broek@rivm.nl
Ingrid V F
IV
van den Broek
Elfi E H G
EE
Brouwers
Hannelore M
HM
Götz
Jan E A M
JE
van Bergen
Eline L M
EL
Op de Coul
Johannes S A
JS
Fennema
Rik H
RH
Koekenbier
Lydia L
LL
Pars
Sander M
SM
van Ravesteijn
Christian J P A
CJ
Hoebe
D000293:Adolescent; D000328:Adult; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000453:epidemiology* / Q000628:therapy; D002692:Chlamydia trachomatis / Q000302:isolation & purification*; D003140:Communicable Disease Control / Q000191:economics* / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D009426:Netherlands / Q000453:epidemiology; D010342:Patient Acceptance of Health Care; D018570:Risk Assessment; D012307:Risk Factors; D012424:Rural Population; D011795:Surveys and Questionnaires; D055815:Young Adult