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THE

BREAST

ORIGINAL ARTICLE

Profile of women not attending in the SwissMammography Screening Pilot Programme

J.-L. Bulliarda,*,1, J.-P. de Landtsheerb, F. Levia,c

aUnite d’Epidemiologie du Cancer, Institut Universitaire de Medecine Sociale et Preventive, rue du Bugnon17, 1005 Lausanne, SwitzerlandbFondation pour le Depistage du Cancer du Sein, 1005 Lausanne, SwitzerlandcRegistre Vaudois des Tumeurs, Institut Universitaire de Medecine Sociale et Preventive, 1011 Lausanne,Switzerland

Received 1 September 2003; received in revised form 20 January 2004; accepted 1 March 2004

Summary The Swiss Mammography Screening Pilot Programme was conductedbetween 1993 and 1998 in three areas of the French-speaking canton of Vaud. Socio-demographic characteristics were available for the whole of the target populationand were used to identify determinants of initial (in the first round) and repeated (inboth first and second rounds) non-attendance by means of logistic regressionanalyses. Initial non-attendance was higher among non-Swiss, single or divorced/separated women, and increased with distance between the residence and thescreening centre. Being single and aged 65–70, not living in the vicinity of thescreening centre and replying to decline the invitation to the initial screening sessionsignificantly increased the odds of persisting in non-attendance for screening withinthe programme. Factors such as age, nationality, marital status and screening centrediffered in their influence on initial and repeated non-attendance, and the type ofreply to the invitation was strongly predictive of non-attendance in the next round.& 2004 Elsevier Ltd. All rights reserved.

Introduction

Between 1993 and 1998, a pilot mammographyscreening programme carried out in westernSwitzerland (French-speaking canton of Vaud)demonstrated the feasibility and acceptability ofan organised screening intervention within the

liberal healthcare system in Switzerland,1 whereopportunistic breast cancer screening is wide-spread.2 This was the first ever organised cancerscreening programme to be established in Switzer-land, a country in which the breast cancermortality rate is high.3 This experimental projectcontributed to the implementation of three can-ton-wide mammography screening programmesstarted in 1999.

This pilot programme was initiated and sup-ported locally by leading physicians and publichealth authorities, and the service was free of costto participants. This meant that the environment

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KEYWORDS

Mass screening;

Mammography;

Breast neoplasm;

Programme;

Participation;

Switzerland;

Evaluation

*Corresponding author. Fax: þ 41-21-3147373.E-mail address: jean-luc.bulliard@hospvd.ch (J.-L. Bulliard).1Supported by a fellowship from the Swiss National Science

Foundation (no. 32-63130.00). The Vaud screening pilot projectreceived support from the Swiss and the Vaud Cancer Leagues.

0960-9776/$ - see front matter & 2004 Elsevier Ltd. All rights reserved.doi:10.1016/j.breast.2004.03.001

The Breast (2004) 13, 284–289

for screening promotion was more favourable thanit would have been in a wider population-basedprogramme. While screening attendance has beenabundantly investigated, non-attendance has re-ceived less attention, and studies of predictors ofparticipation have rarely addressed the contribu-tion of these factors to non-participation (reviewedelsewhere4,5). Predictors of non-attendance havediffered across studies, indicating a local, culturalcomponent in non-attendance, or at least suggest-ing that the identification of factors affecting non-attendance is complicated. Apart from a fewexceptions,6,7 studies on non-attendance haverelied on self-administered questionnaires andinterviews of small samples, and have thus beensubject to potential selection biases.

The aims of this study were two-fold. The firstaim was to identify socio-demographic determi-nants of initial non-attendance in the Swiss pilotprogramme. Data routinely collected by the Swisspopulation registers made it possible to analysesocio-demographic characteristics for the wholetarget population. The second aim was to exploresubsequent participation status among initial non-attendees and examine the factors associated withrepeated non-attendance. In particular, we inves-tigated what type of reaction/reply to the first-round invitation and what socio-demographiccharacteristics were related to repeated non-attendance. Determining what factors influencewomen’s decisions to decline a screening invitationmight suggest interventions that would increaseparticipation. To our knowledge, predictors ofinitial and subsequent non-attendance in an orga-nised mammography screening programme havenot yet been simultaneously reported.

Materials and methods

In the Swiss pilot programme, about 15,000 womenaged 50–69 and residing in the three districts ofAigle, Aubonne and Morges were personally invitedevery 2 years to attend a mammography examina-tion. The screening test was cost free to eachperson invited but had to be carried out in one oftwo dedicated radiology centres located withinpublic hospitals (in Morges for Aubonne and Morgesdistricts residents, in Aigle for others). Therecruitment, invitation and screening procedureshave been detailed elsewhere.1,8 Overall, partici-pation was 43% in the first and 47% in the secondround of screening.

Data made available from the population regis-ters included identity, date of birth, domicile,

marital status, nationality and occupation (of eachwoman and her partner). The distance between thedomicile and the radiology centre was determinedfrom a map. Age was calculated at the timeinvitations were issued for each screening round.

A preliminary analysis showed that occupation, aproxy for socio-economic status, was insufficientlydefined (unemployed or retired) for a substantialfraction of the target population and that the levelof completeness was dependent on participationstatus (the information was more comprehensiveamong attendees, as it was sometimes updatedduring the examination session), which led to theexclusion of this variable. For the purposes of thestudy, the 10 municipal population registers forwhich records with unknown marital status ornationality exceeded 10% were subsequently re-contacted; missing information was obtained in thisway in most instances (one municipality was unableto provide these data, and its 679 residents wereexcluded from the analyses regardless of theirparticipation status).

Ineligibility criteria were a personal history ofbreast cancer, current breast symptoms and anycurrent serious health problem. For this study, onlyeligible women invited between 1 October 1993and 30 September 1995 (first screening round) wereincluded. Most of the women recruited subse-quently had just turned 50 or had newly arrivedin the programme’s catchment area, and thesewere probably not exposed to the same amount ofinformation about screening as those invited ear-lier. An initial non-attendee was defined as ascreen-eligible woman who did not attend the firstround following dispatch of a letter of invitationand reminder letters. Women who were invited butattended neither of the first two screening roundswere called repeated non-attendees. Women whoanticipated their invitations and initiated their ownscreening appointments were excluded from theanalysis of initial non-attendance (n ¼ 145). Infact, the lack of a formal invitation precludedthem from receiving the screening informationmaterial sent with the invitation.

Predictors of initial and repeated non-atten-dance were obtained by logistic regression model-ling. A univariate analysis of the effects of theindependent variables on the odds of being a non-attendee was first performed. Variables with anoverall P-value smaller than 0.25 were kept formultivariate analyses.9 The main-effects modelwas obtained by successive applications of apurposeful selection procedure,10 and only statis-tically significant variables were retained in themodels. Finally, the statistical significance ofrelevant interactions was tested from the main-

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Profile of women not attending for screening in the Swiss Mammography Screening Pilot Programme 285

effects model, and the goodness-of-fit of themodels for initial and repeated non-attendancewas assessed.

Results

Socio-demographic characteristics of the 10,783eligible first-round invitees are presented in Table 1along with odds ratios (ORs) for initial non-attendance. Non-attendance per se was highestamong non-Swiss women and those who weresingle, separated or divorced. Non-attendanceincreased with increasing distance of the residencefrom the screening centre. Results derived from themultivariate analysis did not materially modify theORs for non-attendance, although age was no

longer indicative of non-attendance (P ¼ 0:22).After adjustment, the probability of not attendingthe pilot programme was highest among womenwho lived in the Aigle district (OR ¼ 1:17), were ofnon-Swiss citizenship (OR ¼ 1:54), and were single(OR ¼ 1:31) or divorced or separated (OR ¼ 1:39).The decrease in non-attendance with increasingproximity to the screening centre persisted. Theinfluence of the distance from the domicile to thescreening centre on attendance/non-attendancediffered with marital status and with residence inthe Aigle or the Morges/Aubonne district (statisti-cally significant interactions between screeningcentre/civil status and distance, not shown).

Some 16% of initial non-attendees were screenedin the second round. Factors associated withrepeated non-attendance are given in Table 2.Single women (OR ¼ 1:66), those aged 65 or more

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Table 1 Number of eligible women invited for first screening round (N), proportion of attendees, and crude andadjusted odds ratio or with 95% confidence interval (CI) for socio-demographic predictors of initial non-attendance in the Swiss Mammography Screening Pilot Programme.

Variable, response category N Attendees (%)n OR for non-attendance 95% CI

Crude Adjustedw

Screening centreMorges 7627 48.0 1.00 1.00Aigle 3156 42.7 1.24 1.17 1.07–1.28

Distance from screening centre (km)o5 3486 51.7 1.00 1.005–10 2721 47.9 1.16 1.21 1.09–1.3411–20 3558 41.9 1.48 1.46 1.32–1.61420 1018 40.2 1.59 1.57 1.36–1.83

Age (years) NS50–54 3995 45.2 1.0055–59 2478 46.0 0.9760–64 2173 48.5 0.8865–70 2137 47.3 0.92

Nationalityz

Swiss 8822 48.0 1.00 1.00Other 1517 37.9 1.51 1.54 1.37–1.72

Marital statusz

Married 7150 48.1 1.00 1.00Single 639 41.1 1.33 1.31 1.11–1.55Widowed 1435 45.9 1.09 1.09 0.97–1.23Divorced/separated 1328 40.8 1.35 1.39 1.23–1.57

NS: not significant (age not kept in the multivariate model).n451 observations with missing data (either for nationality or for marital status) were excluded from these calculations and themultivariate analysis.wEach variable was adjusted for all other statistically significant factors included in the Table.z444 cases with unknown nationality were excluded.z231 cases with unknown marital status were excluded.

286 J.-L. Bulliard et al.

(OR ¼ 1:60), and those not residing in the vicinityof the screening centre (OR ¼ 1:37) were the mostlikely to persist in not attending the programme.Respondents who were under medical surveillanceor just did not come to their scheduled appoint-ment were, respectively, two and five times aslikely as those who did not reply to their first-roundinvitation to attend the next screening round.Respondents who had declined to participate inthe previous round made up the subgroup of womenwho were the least likely to attend the subsequentround. Screening centre and nationality did notsignificantly influence repeated non-attendance.

Discussion

This study has identified relevant socio-demo-graphic factors that influence non-attendance forscreening within a free mammography screeningprogramme in western Switzerland, where therehad been no previous initiatives of this kind.Differences in the influence of socio-demographicfactors on initial and repeated non-attendancewere observed. However, the pattern of non-attendance might have been affected by theselective setting of this pilot programme.

Several socio-demographic characteristics con-tributed to initial non-attendance. An inverserelationship between attendance and geographicaldistance from the screening centre was alsoreported in some other programmes.11–14 In an-other study, non-attendees were shown to perceivetravel time to the screening centre as longer thanattendees did.15 Whether distance was a disincen-tive to participation is unclear, given that appoint-ments could be made at the women’s convenienceand only 11% of the target population lived fartherthan 20 km from their allocated screening centre. Apreliminary, small survey indicated that only 6% ofnon-attendees ascribed their non-participation inthe pilot programme to difficulties in accessing thescreening centre.16 The higher initial attendance inMorges than Aigle was probably due to the activeinvolvement of the former centre in the setting upof the pilot programme. The simultaneous wideravailability of opportunistic screening in the semi-urban region of Morges than in the predominantlyalpine district of Aigle could explain the differenteffect of distance on initial non-attendance ob-served between these areas (statistically significantinteraction term).

The overall absence of any significant effect ofage corroborated results from some Europeanprogrammes17,18 but was at variance with results

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Table 2 Crude and adjusted odds ratios (OR), with 95% confidence intervals (CI) for statistically significantpredictors of repeated non-attendance in the Swiss Mammography Screening Pilot Programme.

Variable Crude OR Adjusted ORn P-value

Age (years) o0.00150–54 1.00 1.00 (reference)55–59 0.99 0.96 (0.78–1.17)60–64 0.94 0.90 (0.73–1.11)65–70 1.69 1.60 (1.24–2.06)

Lived o5 km from the screening centre o0.001Yes 1.00 1.00 (reference)No 1.32 1.37 (1.16–1.62)

Marital status o0.01Married 1.00 1.00 (reference)Single 1.84 1.66 (1.13–2.43)Widowed 0.91 0.74 (0.58–0.95)Divorced/separated 0.92 0.87 (0.69–1.09)

Replied to invitation to first round of screening examinations o0.001No 1.00 1.00 (reference)Yes, already under medical surveillance 0.45 0.46 (0.39–0.54)Yes, declined 1.54 1.39 (0.85–2.26)Yes, but did not keep the appointment 0.20 0.19 (0.11–0.35)

nEach variable was adjusted for all other factors in the Table.

Profile of women not attending for screening in the Swiss Mammography Screening Pilot Programme 287

from others, which indicated an increase in non-attendance with age.6,19 Younger non-attendeeswere more likely to be in the pre- or peri-menopausal period, and thus to be visiting agynaecologist regularly, than older women. Thisindividual follow-up may include regular mammo-graphy screening performed outside the pilotprogramme. The sparse data available in Switzer-land suggest that opportunistic screening might bemore prevalent among women in the 50–59 agegroup than among 60–69 year olds.2 This couldpartly explain the 10% lower odds of initial non-attendance among women in their sixties than in50–54 year olds.

The greater likelihood of non-attendance amongnon-Swiss women was consistent with experiencerecorded in Sweden, where non-attendance waslowest among females of Swedish origin,6 andAustralia, where non-attendance was commensu-rate with the proportion of non-English-speakinghouseholds.12 A large proportion of foreigners didnot have French as their mother tongue, thelanguage in which the information material andthe invitations were written. There may have beena lower chance of reaching and sensitising thesewomen even though the option of being giveninformation orally in any of eight languages wasoffered.1

Married women and widows were the most likelyto attend the Swiss pilot programme. This is inkeeping with observations recorded in most Eur-opean studies, which reported an associationbetween marital status and attendance.18,20–22

Inconsistent relationships between marital statusand screening attendance were generally foundwhen potential socio-demographic confounderswere not controlled for.4 The lower non-attendanceamong married women and widows could reflect ahigher degree of social support and interaction,6 agreater encouragement to participate from thespouse or a family member,23 a feeling of respon-sibility for family and a greater concern withhealth.

The interpretation of predictors of initial non-attendance can largely be extended to socio-demographic determinants of repeated non-atten-dance. Repeated non-attendees may be the hardestsegment of the population to reach. Only one initialnon-attendee in six participated in the nextscreening round 2 years later. This proportion mightbe even lower in an extended screening pro-gramme, where the screening environment is likelyto be less favourable than in this pilot programme.Intervention focusing on women who attend forbreast screening only irregularlyFor not at all-Fi.e., the group likely to derive the most benefit

from screening participation, would first requiredifferentiation between these unscreened womenand non-attendees who are regularly screenedoutside the programme. This lack of informationis a serious weakness for the evaluation of the SwissMammography Screening Pilot Programme.

The strengths of this study are that the wholetarget population is included in multivariate ana-lyses, which minimises any potential selection bias,and that official, socio-demographic data are usedrather than self-reported information. In theabsence of specific screening promotion for initialnon-attendees, one might surmise that women whoattended for the first time in the second roundneeded more time to be sensitised or to reach theirdecision. The choice/change between opportunis-tic and organised screening might have been harderto make for older women, particularly those aged65 or over, owing to their longer medical experi-ence of screening. Further, the offer of organisedscreening, where participants need not have con-tact with a medical doctor, might suit youngerwomen better.

Whether non-attendance can be ascribed primar-ily to the known socio-demographic features or toother factors is not clear. This study was confined towomen who were all, theoretically, exposed to thesame information about the programme. On theone hand, the moderate effect on non-attendanceobserved for socio-demographic factors could re-flect the impact of a rather wide and homogeneousacceptance of the mammography screening pro-gramme among the target population and healthprofessionals. This would support the way the pilotprogramme was promoted. In this respect, theexclusion of occupationFa proxy for socio-eco-nomic statusFfrom our analyses may represent apotentially important limitation. On the otherhand, a potential, large impact of unmeasuredfactors, such as knowledge, beliefs or anxiety, onnon-attendance cannot be excluded.4,5 The type ofreply to the initial invitation supports the psycho-social theory placing women at different stages ofmammography take-up.24,25 Initial non-attendeeswho simply did not keep their appointments(possibly in contemplation to perform mammogra-phy screening) were the most likely to attend thenext screening round, whereas initial non-atten-dees who made the effort to reply decliningparticipation were the least likely to attend nexttime, as might be expected. Thus, the type of replyis a good predictor of future non-attendance, andthis information may be helpful when personalisingand optimising invitation strategies in the future.

In summary, this study indicates that non-attendance within the Swiss pilot programme

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differed with nationality, marital status, screeningcentre and its proximity to domicile, and thatrepeated non-attendance prevailed among initialnon-attendees and was determined both by socio-demographic characteristics and reaction to theinvitation for the previous round of screening.

Acknowledgements

The staff of the Breast Cancer Screening Founda-tion of Lausanne is thanked for their collaborationthroughout the project, Ms. C. Cesco for retrievingand compiling socio-demographic records, Mr. R.Leibenguth for extracting the screening datafile,and Mr. G. van Melle for statistical advice. Thehelpful comments of a peer reviewer are gratefullyacknowledged.

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