Public Health
(1990), 104, 239-247
© The Society of Public Health, 1990
Mobile Breast Screening: Factors Affecting Uptake, Efforts to Increase Response and Acceptability D. C. Haiart, 1 L. M c K e n z i e , 2 J. H e n d e r s o n , 2 W. P o l l o c k , 3 D . V . M c Q u e e n , 4 M. M. Roberts 1 a n d Sir A. P. M. Forrest ~
7Department of Surgery, Roya/ Infirmary of Edinburgh, 2Hea/th Economics Research Unit, University of Aberdeen; 3General Practitioner, Port Seton Hea/th Centre, Port Seton, Lothian; 4Unit in Hea/th and Behavioura/ Change, University of Edinburgh
In 1986, a breast screening project was set up to assess the feasibility of mobile breast screening in rural areas near Edinburgh. Secondary objectives included a study of factors affecting uptake, ways in which uptake might be encouraged and a study of the acceptability of this form of screening. This paper deals with the results of studies dealing with secondary objectives. We found that response rates to opportunistic screening was poor, 5,631 attenders out of 23,229 eligible women (24.2%). This was especially so in older women. Distance proved to be the single most significant factor affecting uptake, but car and house ownership were also highly significantly correlated with response. Leaflet drops had no demonstrable effect on response, but personal invitations by general practitioners produced a 75% response rate in women 50-64 who had failed to attend on the van's previous visit. Attenders found this form of screening both convenient and acceptable.
Introduction In the U K a national p r o g r a m m e for breast screening is underway. W o m e n o f 50-64 years o f age are being invited every 3 years for m a m m o g r a p h i c screening. The definition of the population to be invited is by the construction o f registers by Family Practitioner Committees in England and Wales, and by Area Health Boards in Scotland and Northern Ireland, which will be checked by general practitioners. A similar system was used to invite w o m e n in the Trial o f Early Detection o f Breast Cancer in which Edinburgh and Guildford were the two centres offering periodic screening by clinical examination and m a m m o g r a p h y 1. The attendance rates in these two cities varied, being 60% in Edinburgh and 72% in Guildford2; neither o f which approaches those achieved in Sweden (90%) 3-5. In those countries without an organised comprehensive health-care system, such as the National Health Service, the need for breast screening is met by the provision o f clinics which offer m a m m o g r a p h y on demand (and, in most, for payment). It is appreciated that in such 'free-enterprise' systems women must be strongly motivated to attend; and it was to encourage this that mobile screening units were developed in the U S A to take screening into the c o m m u n i t y ~8. Correspondence to: Mr D. C. Haiart, Surgical Registrar, Wards 13/14, Royal Infirmary, Edinburgh EH3 9YW.
240
D . C . Haiart et al.
In 1986, a project was set up in the Lothians, the Lothians Mobile Mammography Project, to study the feasibility and cost of using a mobile mammography unit for screening well women. For this purpose an old mass radiography van was refurbished and equipped with a Mamex DC dedicated mammography unit. From the settlement data of the 1981 Census, 32 towns were considered suitable for visits. The duration of the visit was planned according to the number of eligible women, an assumed 40% attendance rate, a throughput of up to 60 women a day and a minimum stay of 3 days. An itinerary was constructed with the aim of minimising time moving the van, the entire circuit lasting 13 months. In the event this had to be curtailed as a result of practical problems, mainly related to the unreliable performance of our mammography machine, and screening restricted to the 18 towns in East and Mid Lothian. A poster was designed which was approved by the Health Education Officer of the Lothian Health Board for display at the towns to be visited, giving dates and times when screening would be available. The Scottish Womens' Rural Institute, pharmacists, church ministers and the managers of supermarkets, hairdressers, newsagents and other local shops cooperated in distributing and displaying these so that at each location there were some 30 posters displayed at suitable sites. In addition, local newspapers either carried a feature article or an advertisement. In this paper we investigate response rates, some of the socio-demographic characteristics of responders and some factors affecting uptake. We also investigate the institution of two methods to try and increase uptake and the acceptability of this form of screening. Methods and Collection of Data
On attending the van for screening, women were asked a series of questions by a receptionist, the answers to which were entered directly into a microcomputer database. The questions identified ineligible women--those under 40 years of age, those who might be pregnant and those who had had a mammogram in the past 12 months were excluded. The questions enquired about age, marital status, breast symptoms, previous surgery, family history of breast cancer, address and postcode. Women were also asked where they were before visiting the van, how they travelled to the van and how long it took them to get to the van. A separate study was set up to investigate factors affecting uptake of screening in 4 towns, namely Haddington, Loanhead, Penicuik and Roslin. Each town had within it between 1 and 3 postcode sectors, each containing 15 to 20 census enumeration districts (EDs), wl~ich each represented around 100 households. The ED was used as the basic unit for analysis, EDs having been shown to contain homogenous populations allowing comparison between EDs in terms of social and economic characteristics9. Data from the 1981 Census was used to provide, for each ED, the number of women aged 40-64 in residence and the proportion of those who were married; the proportion of households that were owner-occupying and the proportion of households lacking a car. The grid reference of the ED was used to calculate the crow-fly distance between the ED and the location where the van was parked. As well as the above Census data, women who attended the van in these towns were asked to complete a questionnaire. This provided information on access cost of attending, housing tenure, car availability and occupation of the attender. From the above data, the effect on attendance of car ownership, distance from the van, marital status and full-time employment of the attender was determined. The strength of the correlation between each of these variables and attendance rate was
Mobile Breast Screening
241
calculated using multiple regression analysis performed using the SPSS-X computer programme on the Honeywell CP-6 computer at the University of Aberdeen. Additional Studies Two studies were initiated to determine the effect of specific additional measures on attendance. In the first, leaflets were delivered to individual houses (by letterbox) in 2 or 3 postcode sectors (33 out o f 54 EDs) in the town o f Penicuik. These gave information about the project and the availability of the van in that town. Using 1981 Census data to calculate the number o f women aged 40~54 in each ED, the additional effect of the leaflet on attendance rate was determined. In the second study, one town, Port Seton, thought to be representative o f towns in the Lothians and served by one Health Centre was revisited 4 months after the initial visit. On both occasions the van was parked outside the Health Centre from M o n d a y to Friday. One week before the second visit, women aged 5 0 ~ 4 who had not previously attended were sent a personal invitation by their general practitioners. A further 8 women who the GPs felt should not be invited (for r e a s o n s o f ill-health, previous mastectomy, present hospitalisation or current treatment for cancer) did not receive invitations. Acceptability of this form o f screening, was also determined. Prior to screening, each attender was asked for permission to be approached at a later date for either a telephone interview, face to face interview or to complete a written questionnaire. For the purposes of this paper, only answers to questions relating to the convenience o f the van's location, waiting times prior to screening, satisfaction with the way women were treated on the van and whether they would reattend for further screening have been included. Results Attendance rates In all 6,080 women attended for screening. Of these 227 lived outside the area and a further 222 were aged 65 and over and were thus not part o f the eligible population, leaving a total of 5,631 eligible women who were screened. Response rates in relation to age are given in Table I. Overall only 5,631 out o f 23,229 eligible women (24.2%) attended for screening. There is a marked fall-off in attendance with increasing age, and if women under the age o f fifty (the age at which national screening starts) are excluded, the response rate for the ages 50 to 64 is 2,658 women out o f 13,730 (19.4%). Table I Age (Years) 40-44 45-49 50-54 55-59 60-64 Total 40-64
Response rate and age
No. eligible to attend
No. attending
Response rate (%)
4,848 4,651 4,627 4,771 4,332
1,625 1,348 1,102 911 645
33.5 29.0 23.8 19.1 14.9
23,229
5,631
24.2%
D.C. Haiart et al.
242
Other factors & attending women Some features of the 5,853 women resident in East and Mid lothian who attended the van for screening are given in Table II and the time they took to reach the van in Table III.
Four towns study, factors affecting uptake The attendance rates in the 4 towns studied were: Haddington 26.9%, Loanhead 7.7%, Penicuik 42.2% and Roslin 35.0%. Table I1 Some socio-demographic features in 5, 853 attenders living in East and Mid Lothian Number (%) Positive family history* Previous breast surgery Symptomatic Married Single Widowed Divorced/Separated Not recorded At home before screening At work before screening At the shops before screening Elsewhere before screening Walked to van Came by car Came by bus Other transport
339
(5.8)
560 73 5,012 181 384 273 3
(9.6) (1.2) (85.6) (3.1) (6.6) (4.7)
3,262
(55.7)
1,643 (28.1) 521
(8.9)
427 (7.3) 2,729 (46.6) 2,494 (42.6) 554 (9.5) 76 (1.3)
*First degree relative (mother, daughter) Table III
sister,
Time taken to reach the van
Time (rain)
No. of women
(%)
0-9 10-19 20-59 >60
3,237 1,989 595 32
(55.3) (34.0) (10.2) (0.5)
Mobile Breast Screening
243
In Table IV uptake rates are related to car ownership and in Table V to home ownership. Data from EDs for each town have been pooled. The group of women who did attend the breast screening van included a higher proportion o f owner occupiers and car owners than are present in the respective catchment populations. Both these differences were found to be highly significant with a Z2 o f 208, P < 0 . 0 0 1 for car ownership and a Z2 of 488, P < 0 . 0 0 1 for home ownership. Penicuik, Roslin and Haddington were examples o f locations where the van was parked where there was a clearly defined 'natural catchment area'. The abnormally low response rate from Loanhead is thought to be due to its p o o r location as a catchment area and women resident in Loanhead might well have found one of the other places where the van parked more convenient therefore complicating the analysis o f distance. Loanhead was therefore not included in the final regression analysis (Table VI). This indicated that all variables studied were significant and together accounted for 65% of the variance in attendance rates observed between enumeration districts. Distance proved the most significant factor with a t value o f - 3 . 7 , followed by lack o f car ownership ( t = - 2 . 8 ) , full-time employment (t=2.7), and being married (t=2.1) which only just achieved significance. Therefore, the greater the distance and the lower the car ownership level the lower the attendance rate while the higher the proportion o f women married and the higher the proportion in full-time employment, the greater the attendance rate. The elasticity of uptake o f the service with respect to distance, defined as the percentage change in attendance rates relative to a percentage change in distance, was calculated and showed that a 10% increase in distance would lead to a 2.4% reduction in attendance rate.
Table IV
Car ownership in attenders and in the overall population of the 4 towns
Town Attenders Loanhead Penicuik Roslin Haddington
Table V
54/ 65 768/888 149/163 164/189
Car ownership (%) Overall households (83.0) (86.5) (91.4) (86.8)
1182/2052 4150/5920 763/1147 2530/3630
(%) (57.6) (70.1) (66.5) (69.7)
Home ownership in attenders and in the overall population of the 4 towns
Town Attenders Loanhead Penicuik Roslin Haddington
45/ 65 653/888 108/163 112/189
Home ownership (%) Overall households (69.2) (73.5) (66.3) (59.3)
572/2052 2717/5920 454/1147 1191/3630
(%) (27.9) (45.9) (39.6) (32.8)
D. C. Haiart et al.
244 Table Vl
Multiple regression analysis of factors influencing attendance rates in each ED (enumeration district)
Terms in equation
Multiple regression coeffÉcient
in in in in
Penicuik Roslin Haddington no car ownership in distance in full-time employment in married
Coefficient/Standard Error (t)
+ 0.85 + 0.67 +0.22
9.4 6.8 2.7
- 0.21 - 0.24
- 2.8 - 3.7
+ 0.41 + 1.0
2.7 2.1
R 2= 0.65 The regression analysis includes the variables of town, lack of car ownership, distance from screening site, per centage of women married and percentage of women in full employment and analyses their effect on attendance rate.
Additional measures to encourage attendance (i) Leaflet drops T h r e e t h o u s a n d six h u n d r e d a n d f o r t y - o n e h o u s e h o l d s with 1,358 w o m e n aged 40 to 64 received leaflets a n d 2,195 h o u s e h o l d s with 807 w o m e n a g e d 40 to 64 d i d not. T h e r e s p o n s e rates in b o t h g r o u p s is given in T a b l e VII. T h e p o s i t i v e effect o f leaflets a p p e a r s to be o f high statistical significance, t h o u g h the wide v a r i a n c e in a t t e n d a n c e rates in b o t h the leafletted a n d the u n l e a f l e t t e d a r e a s is n o t a b l e . W h e n , h o w e v e r , leaflets were a d d e d as a v a r i a b l e to the t w o f a c t o r s f o u n d to be the m o s t highly significant in the p r e v i o u s r e g r e s s i o n analysis, i.e. d i s t a n c e f r o m the v a n a n d c a r o w n e r s h i p , f u r t h e r regression a n a l y s i s for the t o w n o f P e n i c u i k r e v e a l e d a t v a l u e for leaflets o f o n l y 1.27. T h e r e f o r e w h e n d i s t a n c e f r o m t h e v a n a n d c a r o w n e r s h i p a r e t a k e n i n t o a c c o u n t , leaflets a p p e a r to h a v e n o significant a d d i t i v e effect to r e s p o n s e rates. (ii) Personal invitations T h e g r o u p p r a c t i c e in the t o w n o f P o r t S e t o n h a d 233 w o m e n a g e d b e t w e e n 50 a n d 64. A t the first visit 36 w o m e n a t t e n d e d for screening (15.5°,/o). O n revisiting the town, 141 w o m e n o f the 189 w o m e n ( 7 4 . 6 % ) w h o h a d received p e r s o n a l i n v i t a t i o n s attended. Table VII
Households Women 40-64 Attenders Response rate
The effect of leaflets on attendance rate Leaflets
No leaflets
3,64 i 1,358 590 43.4%
2,195 807 283 35.1%
(Yates' corrected Z2= 14.4 P= < 0.005) Range of response in EDs: 6.7%-84.4%
13.3%-75.0%
Mobile Breast Screening
245
Table VIII Acceptability of mobile screening Location of van convenient?
Very 73.3%
Fairly 24.4%
Not at all 1.9%
Pleased with the way you were treated?
Very 75.5%
Pleased 21.6%
Somewhat 2.7%
Had to queue at the van?
Yes No 63.5% 36.5% (Average waiting time 23.5 minutes)
Would you do it again?
Yes 99.1%
Not at all 0.2%
No 0.9%
Acceptability of mobile screening The data are based on 572 questionnaires which were completed and returned, representing 83.3% of those sent out. Responses to the 4 relevant questions are given in Table VIII. Discussion
When local publicity without personal invitations was used, the attendance rate was only 24.2%, calculated using an estimate of the target population obtained from the Census (1981). This response rate is inferior to that obtained using personal invitations e.g. Edinburgh (60%) and Guildford (72%) 2. The age distribution of attenders is similar to that in other studies of self-referred women ~° and showed a marked fall-off in attendance with increasing age. Eight-six per cent of attenders from East and Mid Lothian were married, a figure about 10% higher than would have been predicted from the General Household Survey I~. A similar trend has been shown among women accepting invitations for breast screening ~2. Neither a positive family history of breast cancer nor previous breast surgery was commoner among our attenders than the general population 13a4. The prevalence of breast symptoms in the population studied was similar to that of the population attending the Edinburgh Breast Screening Clinic (the late M. M. Roberts, personal communication). In the four town study, both home and car ownership were correlated strongly with attendance. These factors reflect socio-economic status which is well known to affect uptake in breast screening programmes 15-~7. Of all the factors analysed in the regression analysis table, distance between home and screening site had the greatest effect on attendance. Time to reach and distance from screening facilities have previously been shown to influence uptake ~8'~9. A ten per cent increase in distance between home and screening site reduced attendance rate by 2.4%. We assumed that crow-fly distance reflected the cost of attending screening. The questionnaire given out to every fifth woman attending (at all locations) dealt with travel mode and cost, travel time, time offwork, other expense and cost incurred by companions. These aggregated costs correlated strongly with
246
D . C . Haiart et al.
cross-fly distance justifying the assumption. Clearly the itinerary of the van should attempt to minimise access cost. Leaflet drops and personal invitations might be expected to increase attendance. This was not so for the former when other variables were taken into account. Personal invitations, however, produced a response rate o f 75% a m o n g women who had failed to attend previously. Mammographic screening on the mobile unit was generally acceptable despite that nearly two thirds of women having to queue for an average o f 23.5 minutes. The importance o f arranging an appointment system is obvious. Van location was very or fairly convenient for 98% o f attenders, nearly half o f whom were able to walk to the site. With few exceptions, women indicated that they would reattend for screening. However as only 24% of the target population did attend, the extent to which the majority of women found the location convenient remains unknown.
Acknowledgements We would like to thank the Scottish Home and Health Department, who provided the grant to fund this project, and the Executive Committee of the Lothian Mobile Mammography Project*. We would also like to thank the general practitioners of Port Seton Health Centre without whose help the personal invitation study could not have been carried out.
References 1. UK Trial of Early Detection of Breast Cancer Group. (1981). Trial of early detection of breast cancer: description of method. British Journal of Cancer, 44, 618-627. 2. UK Trial of Early Detection of Breast Cancer Group. (1988). First results on mortality reduction in the UK trial of early detection of breast cancer. Lancet, ii, 411-416. 3. Lundgren, B. & Jakobsson, S. (1976). Single view mammography: a simple and efficient approach to breast cancer screening. Cancer, 38, 1124-1129. 4. Tahar., L, Gad A., Holmberg L. H., et al. (1985). Reduction in mortality from breast cancer after mass screening with mammography. Lancet, i, 829-832. 5. Lundgren, B. 0979). Population screening by single view mammography in a geographical region. Journal of the National Cancer Institute, 62, 1373-1379. 6. Strax, P. (1972). Female cancer detection mobile unit. Preventive Medicine, l, 422-425. 7. Strax P. (1977). Screening for breast cancer. Clinics in Obstetric and Gynaecology, 20, 781-801. 8. Strax, P. (1980). Strategy (motivation) for detection of early breast cancer. Cancer, 46, 926-929. 9. Carstairs, V. (1981). Small area analysis and health services research. Community Medicine, 3, 131-139. 10. Hohbs, P., Smith, A., George W. D. & Sellwood R.A. (1980). Acceptors and rejectors of an invitation to undergo breast screening compared to those who referred themselves. Journal of Epidemiology & Community Health, 34, 19-22. 11. Office of Population Censuses and Surveys, Social Survey Division. (1987). General Household Survey 1985. HMSO. (GHS no 15). 12. French, K., Porter, A. M. D., Robinson, S. E., McCallum, F.M., Howie, J. G. R. & Roberts, M. M. (1982). Attendance at a breast screening clinic: a problem of administration or attitudes. British Medical Journal, 285, 617-620. 13. Vessey~M. P., Doll, R., Jones, K., McPherson,.K. & Yeates, D. (1979). An epidemiological study of oral contraceptives and breast cancer. British Medical Journal, 1, 1755-1758. 14. Roberts, M. M., French, K. & Dufy, J. (1984). Breast cancer and breast self-examination: what do Scottish women know? Social Science and Medicine, 18, 791-797. *Executive Committee of the Lothians Mobile MammographyProject: Professor Sir Patrick Forrest, the late Dr M. M. Roberts, Dr T. J. Anderson, Mr U. Chetty, Dr A. E. Kirkpatrick.
Mobile Breast Screening
247
15. MacLean, U., Sinfield, D., Klein, S. & Harnden, B. (1984). Women who decline breast screening. Journal of Epidemiology and Community Health, 38, 278-283. 16. Kruse, J. & Phillips, D. M. (1987). Factors influencing women's decision to undergo mammography. Obstetrics and Gynecology, 70, 744-748. 17. Hunt, S. M., Alexander, F. & Roberts, M. M. (1988). Attenders and non-attenders at a breast screening clinic: a comparative study. Public Health, 102, 3-10. 18. Fink, R., Shapiro, S. & Roester, R. (1972). Impacts of efforts to increase participation in repetitive screening for early breast cancer detection. American Journal of Public Health, 62, 328336. 19. Gravelle H. & Simpson, P. (1979). Measuring the benefits of breast cancer screening. Paper presented to the Health Economists' Study Group, University of Aberdeen, 1979.
(1990), 104, 239-247
© The Society of Public Health, 1990
Mobile Breast Screening: Factors Affecting Uptake, Efforts to Increase Response and Acceptability D. C. Haiart, 1 L. M c K e n z i e , 2 J. H e n d e r s o n , 2 W. P o l l o c k , 3 D . V . M c Q u e e n , 4 M. M. Roberts 1 a n d Sir A. P. M. Forrest ~
7Department of Surgery, Roya/ Infirmary of Edinburgh, 2Hea/th Economics Research Unit, University of Aberdeen; 3General Practitioner, Port Seton Hea/th Centre, Port Seton, Lothian; 4Unit in Hea/th and Behavioura/ Change, University of Edinburgh
In 1986, a breast screening project was set up to assess the feasibility of mobile breast screening in rural areas near Edinburgh. Secondary objectives included a study of factors affecting uptake, ways in which uptake might be encouraged and a study of the acceptability of this form of screening. This paper deals with the results of studies dealing with secondary objectives. We found that response rates to opportunistic screening was poor, 5,631 attenders out of 23,229 eligible women (24.2%). This was especially so in older women. Distance proved to be the single most significant factor affecting uptake, but car and house ownership were also highly significantly correlated with response. Leaflet drops had no demonstrable effect on response, but personal invitations by general practitioners produced a 75% response rate in women 50-64 who had failed to attend on the van's previous visit. Attenders found this form of screening both convenient and acceptable.
Introduction In the U K a national p r o g r a m m e for breast screening is underway. W o m e n o f 50-64 years o f age are being invited every 3 years for m a m m o g r a p h i c screening. The definition of the population to be invited is by the construction o f registers by Family Practitioner Committees in England and Wales, and by Area Health Boards in Scotland and Northern Ireland, which will be checked by general practitioners. A similar system was used to invite w o m e n in the Trial o f Early Detection o f Breast Cancer in which Edinburgh and Guildford were the two centres offering periodic screening by clinical examination and m a m m o g r a p h y 1. The attendance rates in these two cities varied, being 60% in Edinburgh and 72% in Guildford2; neither o f which approaches those achieved in Sweden (90%) 3-5. In those countries without an organised comprehensive health-care system, such as the National Health Service, the need for breast screening is met by the provision o f clinics which offer m a m m o g r a p h y on demand (and, in most, for payment). It is appreciated that in such 'free-enterprise' systems women must be strongly motivated to attend; and it was to encourage this that mobile screening units were developed in the U S A to take screening into the c o m m u n i t y ~8. Correspondence to: Mr D. C. Haiart, Surgical Registrar, Wards 13/14, Royal Infirmary, Edinburgh EH3 9YW.
240
D . C . Haiart et al.
In 1986, a project was set up in the Lothians, the Lothians Mobile Mammography Project, to study the feasibility and cost of using a mobile mammography unit for screening well women. For this purpose an old mass radiography van was refurbished and equipped with a Mamex DC dedicated mammography unit. From the settlement data of the 1981 Census, 32 towns were considered suitable for visits. The duration of the visit was planned according to the number of eligible women, an assumed 40% attendance rate, a throughput of up to 60 women a day and a minimum stay of 3 days. An itinerary was constructed with the aim of minimising time moving the van, the entire circuit lasting 13 months. In the event this had to be curtailed as a result of practical problems, mainly related to the unreliable performance of our mammography machine, and screening restricted to the 18 towns in East and Mid Lothian. A poster was designed which was approved by the Health Education Officer of the Lothian Health Board for display at the towns to be visited, giving dates and times when screening would be available. The Scottish Womens' Rural Institute, pharmacists, church ministers and the managers of supermarkets, hairdressers, newsagents and other local shops cooperated in distributing and displaying these so that at each location there were some 30 posters displayed at suitable sites. In addition, local newspapers either carried a feature article or an advertisement. In this paper we investigate response rates, some of the socio-demographic characteristics of responders and some factors affecting uptake. We also investigate the institution of two methods to try and increase uptake and the acceptability of this form of screening. Methods and Collection of Data
On attending the van for screening, women were asked a series of questions by a receptionist, the answers to which were entered directly into a microcomputer database. The questions identified ineligible women--those under 40 years of age, those who might be pregnant and those who had had a mammogram in the past 12 months were excluded. The questions enquired about age, marital status, breast symptoms, previous surgery, family history of breast cancer, address and postcode. Women were also asked where they were before visiting the van, how they travelled to the van and how long it took them to get to the van. A separate study was set up to investigate factors affecting uptake of screening in 4 towns, namely Haddington, Loanhead, Penicuik and Roslin. Each town had within it between 1 and 3 postcode sectors, each containing 15 to 20 census enumeration districts (EDs), wl~ich each represented around 100 households. The ED was used as the basic unit for analysis, EDs having been shown to contain homogenous populations allowing comparison between EDs in terms of social and economic characteristics9. Data from the 1981 Census was used to provide, for each ED, the number of women aged 40-64 in residence and the proportion of those who were married; the proportion of households that were owner-occupying and the proportion of households lacking a car. The grid reference of the ED was used to calculate the crow-fly distance between the ED and the location where the van was parked. As well as the above Census data, women who attended the van in these towns were asked to complete a questionnaire. This provided information on access cost of attending, housing tenure, car availability and occupation of the attender. From the above data, the effect on attendance of car ownership, distance from the van, marital status and full-time employment of the attender was determined. The strength of the correlation between each of these variables and attendance rate was
Mobile Breast Screening
241
calculated using multiple regression analysis performed using the SPSS-X computer programme on the Honeywell CP-6 computer at the University of Aberdeen. Additional Studies Two studies were initiated to determine the effect of specific additional measures on attendance. In the first, leaflets were delivered to individual houses (by letterbox) in 2 or 3 postcode sectors (33 out o f 54 EDs) in the town o f Penicuik. These gave information about the project and the availability of the van in that town. Using 1981 Census data to calculate the number o f women aged 40~54 in each ED, the additional effect of the leaflet on attendance rate was determined. In the second study, one town, Port Seton, thought to be representative o f towns in the Lothians and served by one Health Centre was revisited 4 months after the initial visit. On both occasions the van was parked outside the Health Centre from M o n d a y to Friday. One week before the second visit, women aged 5 0 ~ 4 who had not previously attended were sent a personal invitation by their general practitioners. A further 8 women who the GPs felt should not be invited (for r e a s o n s o f ill-health, previous mastectomy, present hospitalisation or current treatment for cancer) did not receive invitations. Acceptability of this form o f screening, was also determined. Prior to screening, each attender was asked for permission to be approached at a later date for either a telephone interview, face to face interview or to complete a written questionnaire. For the purposes of this paper, only answers to questions relating to the convenience o f the van's location, waiting times prior to screening, satisfaction with the way women were treated on the van and whether they would reattend for further screening have been included. Results Attendance rates In all 6,080 women attended for screening. Of these 227 lived outside the area and a further 222 were aged 65 and over and were thus not part o f the eligible population, leaving a total of 5,631 eligible women who were screened. Response rates in relation to age are given in Table I. Overall only 5,631 out o f 23,229 eligible women (24.2%) attended for screening. There is a marked fall-off in attendance with increasing age, and if women under the age o f fifty (the age at which national screening starts) are excluded, the response rate for the ages 50 to 64 is 2,658 women out o f 13,730 (19.4%). Table I Age (Years) 40-44 45-49 50-54 55-59 60-64 Total 40-64
Response rate and age
No. eligible to attend
No. attending
Response rate (%)
4,848 4,651 4,627 4,771 4,332
1,625 1,348 1,102 911 645
33.5 29.0 23.8 19.1 14.9
23,229
5,631
24.2%
D.C. Haiart et al.
242
Other factors & attending women Some features of the 5,853 women resident in East and Mid lothian who attended the van for screening are given in Table II and the time they took to reach the van in Table III.
Four towns study, factors affecting uptake The attendance rates in the 4 towns studied were: Haddington 26.9%, Loanhead 7.7%, Penicuik 42.2% and Roslin 35.0%. Table I1 Some socio-demographic features in 5, 853 attenders living in East and Mid Lothian Number (%) Positive family history* Previous breast surgery Symptomatic Married Single Widowed Divorced/Separated Not recorded At home before screening At work before screening At the shops before screening Elsewhere before screening Walked to van Came by car Came by bus Other transport
339
(5.8)
560 73 5,012 181 384 273 3
(9.6) (1.2) (85.6) (3.1) (6.6) (4.7)
3,262
(55.7)
1,643 (28.1) 521
(8.9)
427 (7.3) 2,729 (46.6) 2,494 (42.6) 554 (9.5) 76 (1.3)
*First degree relative (mother, daughter) Table III
sister,
Time taken to reach the van
Time (rain)
No. of women
(%)
0-9 10-19 20-59 >60
3,237 1,989 595 32
(55.3) (34.0) (10.2) (0.5)
Mobile Breast Screening
243
In Table IV uptake rates are related to car ownership and in Table V to home ownership. Data from EDs for each town have been pooled. The group of women who did attend the breast screening van included a higher proportion o f owner occupiers and car owners than are present in the respective catchment populations. Both these differences were found to be highly significant with a Z2 o f 208, P < 0 . 0 0 1 for car ownership and a Z2 of 488, P < 0 . 0 0 1 for home ownership. Penicuik, Roslin and Haddington were examples o f locations where the van was parked where there was a clearly defined 'natural catchment area'. The abnormally low response rate from Loanhead is thought to be due to its p o o r location as a catchment area and women resident in Loanhead might well have found one of the other places where the van parked more convenient therefore complicating the analysis o f distance. Loanhead was therefore not included in the final regression analysis (Table VI). This indicated that all variables studied were significant and together accounted for 65% of the variance in attendance rates observed between enumeration districts. Distance proved the most significant factor with a t value o f - 3 . 7 , followed by lack o f car ownership ( t = - 2 . 8 ) , full-time employment (t=2.7), and being married (t=2.1) which only just achieved significance. Therefore, the greater the distance and the lower the car ownership level the lower the attendance rate while the higher the proportion o f women married and the higher the proportion in full-time employment, the greater the attendance rate. The elasticity of uptake o f the service with respect to distance, defined as the percentage change in attendance rates relative to a percentage change in distance, was calculated and showed that a 10% increase in distance would lead to a 2.4% reduction in attendance rate.
Table IV
Car ownership in attenders and in the overall population of the 4 towns
Town Attenders Loanhead Penicuik Roslin Haddington
Table V
54/ 65 768/888 149/163 164/189
Car ownership (%) Overall households (83.0) (86.5) (91.4) (86.8)
1182/2052 4150/5920 763/1147 2530/3630
(%) (57.6) (70.1) (66.5) (69.7)
Home ownership in attenders and in the overall population of the 4 towns
Town Attenders Loanhead Penicuik Roslin Haddington
45/ 65 653/888 108/163 112/189
Home ownership (%) Overall households (69.2) (73.5) (66.3) (59.3)
572/2052 2717/5920 454/1147 1191/3630
(%) (27.9) (45.9) (39.6) (32.8)
D. C. Haiart et al.
244 Table Vl
Multiple regression analysis of factors influencing attendance rates in each ED (enumeration district)
Terms in equation
Multiple regression coeffÉcient
in in in in
Penicuik Roslin Haddington no car ownership in distance in full-time employment in married
Coefficient/Standard Error (t)
+ 0.85 + 0.67 +0.22
9.4 6.8 2.7
- 0.21 - 0.24
- 2.8 - 3.7
+ 0.41 + 1.0
2.7 2.1
R 2= 0.65 The regression analysis includes the variables of town, lack of car ownership, distance from screening site, per centage of women married and percentage of women in full employment and analyses their effect on attendance rate.
Additional measures to encourage attendance (i) Leaflet drops T h r e e t h o u s a n d six h u n d r e d a n d f o r t y - o n e h o u s e h o l d s with 1,358 w o m e n aged 40 to 64 received leaflets a n d 2,195 h o u s e h o l d s with 807 w o m e n a g e d 40 to 64 d i d not. T h e r e s p o n s e rates in b o t h g r o u p s is given in T a b l e VII. T h e p o s i t i v e effect o f leaflets a p p e a r s to be o f high statistical significance, t h o u g h the wide v a r i a n c e in a t t e n d a n c e rates in b o t h the leafletted a n d the u n l e a f l e t t e d a r e a s is n o t a b l e . W h e n , h o w e v e r , leaflets were a d d e d as a v a r i a b l e to the t w o f a c t o r s f o u n d to be the m o s t highly significant in the p r e v i o u s r e g r e s s i o n analysis, i.e. d i s t a n c e f r o m the v a n a n d c a r o w n e r s h i p , f u r t h e r regression a n a l y s i s for the t o w n o f P e n i c u i k r e v e a l e d a t v a l u e for leaflets o f o n l y 1.27. T h e r e f o r e w h e n d i s t a n c e f r o m t h e v a n a n d c a r o w n e r s h i p a r e t a k e n i n t o a c c o u n t , leaflets a p p e a r to h a v e n o significant a d d i t i v e effect to r e s p o n s e rates. (ii) Personal invitations T h e g r o u p p r a c t i c e in the t o w n o f P o r t S e t o n h a d 233 w o m e n a g e d b e t w e e n 50 a n d 64. A t the first visit 36 w o m e n a t t e n d e d for screening (15.5°,/o). O n revisiting the town, 141 w o m e n o f the 189 w o m e n ( 7 4 . 6 % ) w h o h a d received p e r s o n a l i n v i t a t i o n s attended. Table VII
Households Women 40-64 Attenders Response rate
The effect of leaflets on attendance rate Leaflets
No leaflets
3,64 i 1,358 590 43.4%
2,195 807 283 35.1%
(Yates' corrected Z2= 14.4 P= < 0.005) Range of response in EDs: 6.7%-84.4%
13.3%-75.0%
Mobile Breast Screening
245
Table VIII Acceptability of mobile screening Location of van convenient?
Very 73.3%
Fairly 24.4%
Not at all 1.9%
Pleased with the way you were treated?
Very 75.5%
Pleased 21.6%
Somewhat 2.7%
Had to queue at the van?
Yes No 63.5% 36.5% (Average waiting time 23.5 minutes)
Would you do it again?
Yes 99.1%
Not at all 0.2%
No 0.9%
Acceptability of mobile screening The data are based on 572 questionnaires which were completed and returned, representing 83.3% of those sent out. Responses to the 4 relevant questions are given in Table VIII. Discussion
When local publicity without personal invitations was used, the attendance rate was only 24.2%, calculated using an estimate of the target population obtained from the Census (1981). This response rate is inferior to that obtained using personal invitations e.g. Edinburgh (60%) and Guildford (72%) 2. The age distribution of attenders is similar to that in other studies of self-referred women ~° and showed a marked fall-off in attendance with increasing age. Eight-six per cent of attenders from East and Mid Lothian were married, a figure about 10% higher than would have been predicted from the General Household Survey I~. A similar trend has been shown among women accepting invitations for breast screening ~2. Neither a positive family history of breast cancer nor previous breast surgery was commoner among our attenders than the general population 13a4. The prevalence of breast symptoms in the population studied was similar to that of the population attending the Edinburgh Breast Screening Clinic (the late M. M. Roberts, personal communication). In the four town study, both home and car ownership were correlated strongly with attendance. These factors reflect socio-economic status which is well known to affect uptake in breast screening programmes 15-~7. Of all the factors analysed in the regression analysis table, distance between home and screening site had the greatest effect on attendance. Time to reach and distance from screening facilities have previously been shown to influence uptake ~8'~9. A ten per cent increase in distance between home and screening site reduced attendance rate by 2.4%. We assumed that crow-fly distance reflected the cost of attending screening. The questionnaire given out to every fifth woman attending (at all locations) dealt with travel mode and cost, travel time, time offwork, other expense and cost incurred by companions. These aggregated costs correlated strongly with
246
D . C . Haiart et al.
cross-fly distance justifying the assumption. Clearly the itinerary of the van should attempt to minimise access cost. Leaflet drops and personal invitations might be expected to increase attendance. This was not so for the former when other variables were taken into account. Personal invitations, however, produced a response rate o f 75% a m o n g women who had failed to attend previously. Mammographic screening on the mobile unit was generally acceptable despite that nearly two thirds of women having to queue for an average o f 23.5 minutes. The importance o f arranging an appointment system is obvious. Van location was very or fairly convenient for 98% o f attenders, nearly half o f whom were able to walk to the site. With few exceptions, women indicated that they would reattend for screening. However as only 24% of the target population did attend, the extent to which the majority of women found the location convenient remains unknown.
Acknowledgements We would like to thank the Scottish Home and Health Department, who provided the grant to fund this project, and the Executive Committee of the Lothian Mobile Mammography Project*. We would also like to thank the general practitioners of Port Seton Health Centre without whose help the personal invitation study could not have been carried out.
References 1. UK Trial of Early Detection of Breast Cancer Group. (1981). Trial of early detection of breast cancer: description of method. British Journal of Cancer, 44, 618-627. 2. UK Trial of Early Detection of Breast Cancer Group. (1988). First results on mortality reduction in the UK trial of early detection of breast cancer. Lancet, ii, 411-416. 3. Lundgren, B. & Jakobsson, S. (1976). Single view mammography: a simple and efficient approach to breast cancer screening. Cancer, 38, 1124-1129. 4. Tahar., L, Gad A., Holmberg L. H., et al. (1985). Reduction in mortality from breast cancer after mass screening with mammography. Lancet, i, 829-832. 5. Lundgren, B. 0979). Population screening by single view mammography in a geographical region. Journal of the National Cancer Institute, 62, 1373-1379. 6. Strax, P. (1972). Female cancer detection mobile unit. Preventive Medicine, l, 422-425. 7. Strax P. (1977). Screening for breast cancer. Clinics in Obstetric and Gynaecology, 20, 781-801. 8. Strax, P. (1980). Strategy (motivation) for detection of early breast cancer. Cancer, 46, 926-929. 9. Carstairs, V. (1981). Small area analysis and health services research. Community Medicine, 3, 131-139. 10. Hohbs, P., Smith, A., George W. D. & Sellwood R.A. (1980). Acceptors and rejectors of an invitation to undergo breast screening compared to those who referred themselves. Journal of Epidemiology & Community Health, 34, 19-22. 11. Office of Population Censuses and Surveys, Social Survey Division. (1987). General Household Survey 1985. HMSO. (GHS no 15). 12. French, K., Porter, A. M. D., Robinson, S. E., McCallum, F.M., Howie, J. G. R. & Roberts, M. M. (1982). Attendance at a breast screening clinic: a problem of administration or attitudes. British Medical Journal, 285, 617-620. 13. Vessey~M. P., Doll, R., Jones, K., McPherson,.K. & Yeates, D. (1979). An epidemiological study of oral contraceptives and breast cancer. British Medical Journal, 1, 1755-1758. 14. Roberts, M. M., French, K. & Dufy, J. (1984). Breast cancer and breast self-examination: what do Scottish women know? Social Science and Medicine, 18, 791-797. *Executive Committee of the Lothians Mobile MammographyProject: Professor Sir Patrick Forrest, the late Dr M. M. Roberts, Dr T. J. Anderson, Mr U. Chetty, Dr A. E. Kirkpatrick.
Mobile Breast Screening
247
15. MacLean, U., Sinfield, D., Klein, S. & Harnden, B. (1984). Women who decline breast screening. Journal of Epidemiology and Community Health, 38, 278-283. 16. Kruse, J. & Phillips, D. M. (1987). Factors influencing women's decision to undergo mammography. Obstetrics and Gynecology, 70, 744-748. 17. Hunt, S. M., Alexander, F. & Roberts, M. M. (1988). Attenders and non-attenders at a breast screening clinic: a comparative study. Public Health, 102, 3-10. 18. Fink, R., Shapiro, S. & Roester, R. (1972). Impacts of efforts to increase participation in repetitive screening for early breast cancer detection. American Journal of Public Health, 62, 328336. 19. Gravelle H. & Simpson, P. (1979). Measuring the benefits of breast cancer screening. Paper presented to the Health Economists' Study Group, University of Aberdeen, 1979.
