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

ARTICLE IN PRESS The Breast (2004) 13, 284–289

THE

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ORIGINAL ARTICLE

Profile of women not attending in the Swiss Mammography Screening Pilot Programme J.-L. Bulliarda,*,1, J.-P. de Landtsheerb, F. Levia,c a

´ d’Epide ´miologie du Cancer, Institut Universitaire de Me ´decine Sociale et Pre ´ventive, rue du Bugnon Unite 17, 1005 Lausanne, Switzerland b ´pistage du Cancer du Sein, 1005 Lausanne, Switzerland Fondation pour le De c ´decine Sociale et Pre ´ventive, 1011 Lausanne, Registre Vaudois des Tumeurs, Institut Universitaire de Me Switzerland Received 1 September 2003; received in revised form 20 January 2004; accepted 1 March 2004

KEYWORDS Mass screening; Mammography; Breast neoplasm; Programme; Participation; Switzerland; Evaluation

Summary The Swiss Mammography Screening Pilot Programme was conducted between 1993 and 1998 in three areas of the French-speaking canton of Vaud. Sociodemographic characteristics were available for the whole of the target population and were used to identify determinants of initial (in the first round) and repeated (in both first and second rounds) non-attendance by means of logistic regression analyses. Initial non-attendance was higher among non-Swiss, single or divorced/ separated women, and increased with distance between the residence and the screening centre. Being single and aged 65–70, not living in the vicinity of the screening centre and replying to decline the invitation to the initial screening session significantly increased the odds of persisting in non-attendance for screening within the programme. Factors such as age, nationality, marital status and screening centre differed in their influence on initial and repeated non-attendance, and the type of reply 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 mammography screening programme carried out in western Switzerland (French-speaking canton of Vaud) demonstrated the feasibility and acceptability of an organised screening intervention within the *Corresponding author. Fax: þ 41-21-3147373. E-mail address: [email protected] (J.-L. Bulliard). 1 Supported by a fellowship from the Swiss National Science Foundation (no. 32-63130.00). The Vaud screening pilot project received support from the Swiss and the Vaud Cancer Leagues.

liberal healthcare system in Switzerland,1 where opportunistic breast cancer screening is widespread.2 This was the first ever organised cancer screening programme to be established in Switzerland, a country in which the breast cancer mortality rate is high.3 This experimental project contributed to the implementation of three canton-wide mammography screening programmes started in 1999. This pilot programme was initiated and supported locally by leading physicians and public health authorities, and the service was free of cost to participants. This meant that the environment

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for screening promotion was more favourable than it would have been in a wider population-based programme. While screening attendance has been abundantly investigated, non-attendance has received less attention, and studies of predictors of participation have rarely addressed the contribution of these factors to non-participation (reviewed elsewhere4,5). Predictors of non-attendance have differed across studies, indicating a local, cultural component in non-attendance, or at least suggesting that the identification of factors affecting nonattendance is complicated. Apart from a few exceptions,6,7 studies on non-attendance have relied on self-administered questionnaires and interviews of small samples, and have thus been subject to potential selection biases. The aims of this study were two-fold. The first aim was to identify socio-demographic determinants of initial non-attendance in the Swiss pilot programme. Data routinely collected by the Swiss population registers made it possible to analyse socio-demographic characteristics for the whole target population. The second aim was to explore subsequent participation status among initial nonattendees and examine the factors associated with repeated non-attendance. In particular, we investigated what type of reaction/reply to the firstround invitation and what socio-demographic characteristics were related to repeated nonattendance. Determining what factors influence women’s decisions to decline a screening invitation might suggest interventions that would increase participation. To our knowledge, predictors of initial and subsequent non-attendance in an organised mammography screening programme have not yet been simultaneously reported.

Materials and methods In the Swiss pilot programme, about 15,000 women aged 50–69 and residing in the three districts of Aigle, Aubonne and Morges were personally invited every 2 years to attend a mammography examination. The screening test was cost free to each person invited but had to be carried out in one of two dedicated radiology centres located within public hospitals (in Morges for Aubonne and Morges districts residents, in Aigle for others). The recruitment, invitation and screening procedures have been detailed elsewhere.1,8 Overall, participation was 43% in the first and 47% in the second round of screening. Data made available from the population registers included identity, date of birth, domicile,

marital status, nationality and occupation (of each woman and her partner). The distance between the domicile and the radiology centre was determined from a map. Age was calculated at the time invitations were issued for each screening round. A preliminary analysis showed that occupation, a proxy for socio-economic status, was insufficiently defined (unemployed or retired) for a substantial fraction of the target population and that the level of completeness was dependent on participation status (the information was more comprehensive among attendees, as it was sometimes updated during the examination session), which led to the exclusion of this variable. For the purposes of the study, the 10 municipal population registers for which records with unknown marital status or nationality exceeded 10% were subsequently recontacted; missing information was obtained in this way in most instances (one municipality was unable to provide these data, and its 679 residents were excluded from the analyses regardless of their participation status). Ineligibility criteria were a personal history of breast cancer, current breast symptoms and any current serious health problem. For this study, only eligible women invited between 1 October 1993 and 30 September 1995 (first screening round) were included. Most of the women recruited subsequently had just turned 50 or had newly arrived in the programme’s catchment area, and these were probably not exposed to the same amount of information about screening as those invited earlier. An initial non-attendee was defined as a screen-eligible woman who did not attend the first round following dispatch of a letter of invitation and reminder letters. Women who were invited but attended neither of the first two screening rounds were called repeated non-attendees. Women who anticipated their invitations and initiated their own screening appointments were excluded from the analysis of initial non-attendance (n ¼ 145). In fact, the lack of a formal invitation precluded them from receiving the screening information material sent with the invitation. Predictors of initial and repeated non-attendance were obtained by logistic regression modelling. A univariate analysis of the effects of the independent variables on the odds of being a nonattendee was first performed. Variables with an overall P-value smaller than 0.25 were kept for multivariate analyses.9 The main-effects model was obtained by successive applications of a purposeful selection procedure,10 and only statistically significant variables were retained in the models. Finally, the statistical significance of relevant interactions was tested from the main-

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effects model, and the goodness-of-fit of the models for initial and repeated non-attendance was assessed.

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

longer indicative of non-attendance (P ¼ 0:22). After adjustment, the probability of not attending the pilot programme was highest among women who lived in the Aigle district (OR ¼ 1:17), were of non-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 increasing proximity to the screening centre persisted. The influence of the distance from the domicile to the screening centre on attendance/non-attendance differed with marital status and with residence in the Aigle or the Morges/Aubonne district (statistically significant interactions between screening centre/civil status and distance, not shown). Some 16% of initial non-attendees were screened in the second round. Factors associated with repeated non-attendance are given in Table 2. Single women (OR ¼ 1:66), those aged 65 or more

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

Screening centre Morges Aigle

N

Attendees (%)n

OR for non-attendance Crude

Adjusted

95% CI w

7627 3156

48.0 42.7

1.00 1.24

1.00 1.17

1.07–1.28

Distance from screening centre (km) o5 3486 5–10 2721 11–20 3558 420 1018

51.7 47.9 41.9 40.2

1.00 1.16 1.48 1.59

1.00 1.21 1.46 1.57

1.09–1.34 1.32–1.61 1.36–1.83

Age (years) 50–54 55–59 60–64 65–70

3995 2478 2173 2137

45.2 46.0 48.5 47.3

1.00 0.97 0.88 0.92

Nationalityz Swiss Other

8822 1517

48.0 37.9

1.00 1.51

1.00 1.54

1.37–1.72

Marital statusz Married Single Widowed Divorced/separated

7150 639 1435 1328

48.1 41.1 45.9 40.8

1.00 1.33 1.09 1.35

1.00 1.31 1.09 1.39

1.11–1.55 0.97–1.23 1.23–1.57

NS

NS: not significant (age not kept in the multivariate model). n 451 observations with missing data (either for nationality or for marital status) were excluded from these calculations and the multivariate analysis. w Each variable was adjusted for all other statistically significant factors included in the Table. z 444 cases with unknown nationality were excluded. z 231 cases with unknown marital status were excluded.

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

Crude OR

Adjusted ORn

Age (years) 50–54 55–59 60–64 65–70

1.00 0.99 0.94 1.69

1.00 0.96 0.90 1.60

Lived o5 km from the screening centre Yes No

1.00 1.32

1.00 (reference) 1.37 (1.16–1.62)

Marital status Married Single Widowed Divorced/separated

1.00 1.84 0.91 0.92

1.00 1.66 0.74 0.87

(reference) (1.13–2.43) (0.58–0.95) (0.69–1.09)

Replied to invitation to first round of screening examinations No Yes, already under medical surveillance Yes, declined Yes, but did not keep the appointment

1.00 0.45 1.54 0.20

1.00 0.46 1.39 0.19

(reference) (0.39–0.54) (0.85–2.26) (0.11–0.35)

P-value o0.001

(reference) (0.78–1.17) (0.73–1.11) (1.24–2.06) o0.001

o0.01

o0.001

n

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

(OR ¼ 1:60), and those not residing in the vicinity of the screening centre (OR ¼ 1:37) were the most likely to persist in not attending the programme. Respondents who were under medical surveillance or just did not come to their scheduled appointment were, respectively, two and five times as likely as those who did not reply to their first-round invitation to attend the next screening round. Respondents who had declined to participate in the previous round made up the subgroup of women who were the least likely to attend the subsequent round. Screening centre and nationality did not significantly influence repeated non-attendance.

Discussion This study has identified relevant socio-demographic factors that influence non-attendance for screening within a free mammography screening programme in western Switzerland, where there had been no previous initiatives of this kind. Differences in the influence of socio-demographic factors on initial and repeated non-attendance were observed. However, the pattern of nonattendance might have been affected by the selective setting of this pilot programme.

Several socio-demographic characteristics contributed to initial non-attendance. An inverse relationship between attendance and geographical distance from the screening centre was also reported in some other programmes.11–14 In another study, non-attendees were shown to perceive travel time to the screening centre as longer than attendees did.15 Whether distance was a disincentive to participation is unclear, given that appointments could be made at the women’s convenience and only 11% of the target population lived farther than 20 km from their allocated screening centre. A preliminary, small survey indicated that only 6% of non-attendees ascribed their non-participation in the pilot programme to difficulties in accessing the screening centre.16 The higher initial attendance in Morges than Aigle was probably due to the active involvement of the former centre in the setting up of the pilot programme. The simultaneous wider availability of opportunistic screening in the semiurban region of Morges than in the predominantly alpine district of Aigle could explain the different effect of distance on initial non-attendance observed between these areas (statistically significant interaction term). The overall absence of any significant effect of age corroborated results from some European programmes17,18 but was at variance with results

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from others, which indicated an increase in nonattendance with age.6,19 Younger non-attendees were more likely to be in the pre- or perimenopausal period, and thus to be visiting a gynaecologist regularly, than older women. This individual follow-up may include regular mammography screening performed outside the pilot programme. The sparse data available in Switzerland suggest that opportunistic screening might be more prevalent among women in the 50–59 age group than among 60–69 year olds.2 This could partly explain the 10% lower odds of initial nonattendance among women in their sixties than in 50–54 year olds. The greater likelihood of non-attendance among non-Swiss women was consistent with experience recorded in Sweden, where non-attendance was lowest among females of Swedish origin,6 and Australia, where non-attendance was commensurate with the proportion of non-English-speaking households.12 A large proportion of foreigners did not have French as their mother tongue, the language in which the information material and the invitations were written. There may have been a lower chance of reaching and sensitising these women even though the option of being given information orally in any of eight languages was offered.1 Married women and widows were the most likely to attend the Swiss pilot programme. This is in keeping with observations recorded in most European studies, which reported an association between marital status and attendance.18,20–22 Inconsistent relationships between marital status and screening attendance were generally found when potential socio-demographic confounders were not controlled for.4 The lower non-attendance among married women and widows could reflect a higher degree of social support and interaction,6 a greater encouragement to participate from the spouse or a family member,23 a feeling of responsibility for family and a greater concern with health. The interpretation of predictors of initial nonattendance can largely be extended to sociodemographic determinants of repeated non-attendance. Repeated non-attendees may be the hardest segment of the population to reach. Only one initial non-attendee in six participated in the next screening round 2 years later. This proportion might be even lower in an extended screening programme, where the screening environment is likely to be less favourable than in this pilot programme. Intervention focusing on women who attend for breast screening only irregularlyFor not at allFi.e., the group likely to derive the most benefit

J.-L. Bulliard et al.

from screening participation, would first require differentiation between these unscreened women and non-attendees who are regularly screened outside the programme. This lack of information is a serious weakness for the evaluation of the Swiss Mammography Screening Pilot Programme. The strengths of this study are that the whole target population is included in multivariate analyses, which minimises any potential selection bias, and that official, socio-demographic data are used rather than self-reported information. In the absence of specific screening promotion for initial non-attendees, one might surmise that women who attended for the first time in the second round needed more time to be sensitised or to reach their decision. The choice/change between opportunistic and organised screening might have been harder to make for older women, particularly those aged 65 or over, owing to their longer medical experience of screening. Further, the offer of organised screening, where participants need not have contact with a medical doctor, might suit younger women better. Whether non-attendance can be ascribed primarily to the known socio-demographic features or to other factors is not clear. This study was confined to women who were all, theoretically, exposed to the same information about the programme. On the one hand, the moderate effect on non-attendance observed for socio-demographic factors could reflect the impact of a rather wide and homogeneous acceptance of the mammography screening programme among the target population and health professionals. This would support the way the pilot programme was promoted. In this respect, the exclusion of occupationFa proxy for socio-economic statusFfrom our analyses may represent a potentially important limitation. On the other hand, a potential, large impact of unmeasured factors, such as knowledge, beliefs or anxiety, on non-attendance cannot be excluded.4,5 The type of reply to the initial invitation supports the psychosocial theory placing women at different stages of mammography take-up.24,25 Initial non-attendees who simply did not keep their appointments (possibly in contemplation to perform mammography screening) were the most likely to attend the next screening round, whereas initial non-attendees who made the effort to reply declining participation were the least likely to attend next time, as might be expected. Thus, the type of reply is a good predictor of future non-attendance, and this information may be helpful when personalising and optimising invitation strategies in the future. In summary, this study indicates that nonattendance within the Swiss pilot programme

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differed with nationality, marital status, screening centre and its proximity to domicile, and that repeated non-attendance prevailed among initial non-attendees and was determined both by sociodemographic characteristics and reaction to the invitation for the previous round of screening.

Acknowledgements The staff of the Breast Cancer Screening Foundation of Lausanne is thanked for their collaboration throughout the project, Ms. C. Cesco for retrieving and compiling socio-demographic records, Mr. R. Leibenguth for extracting the screening datafile, and Mr. G. van Melle for statistical advice. The helpful comments of a peer reviewer are gratefully acknowledged.

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