Coverage and uptake of systematic postal screening for genital Chlamyd
http://www.100md.com
《英国医生杂志》
1 Department of Primary Care and General Practice, University of Birmingham, Birmingham B15 2TT, 2 Department of Community Based Medicine, University of Bristol, Bristol BS6 6JL, 3 Department of Social Medicine, University of Bristol, Bristol BS8 2PR, 4 Department of Social and Preventive Medicine, University of Berne, Finkenhubelweg 11, Berne, CH-3012, Switzerland, 5 Milne Centre, United Bristol Healthcare Trust, Bristol BS21 7LR, 6 Public Health Laboratory Service, Birmingham B9 5SS, 7 Public Health Laboratory Service, Bristol BS2 8EL
Correspondence to J Macleod j.a.macleod@bham.ac.uk
Objective To measure the coverage and uptake of systematic postal screening for genital Chlamydia trachomatis and the prevalence of infection in the general population in the United Kingdom. To investigate factors associated with these measures.
Design Cross sectional survey of people randomly selected from general practice registers. Invitation to provide a specimen collected at home.
Setting England.
Participants 19 773 men and women aged 16-39 years invited to participate in screening.
Main outcome measures Coverage and uptake of screening; prevalence of chlamydia.
Results Coverage of chlamydia screening was 73% and was lower in areas with a higher proportion of non-white residents. Uptake in 16-24 year olds was 31.5% and was lower in men, younger adults, and practices in disadvantaged areas. Overall prevalence of chlamydia was 2.8% (95%confidence interval 2.2% to 3.4%) in men and 3.6% (3.1% to 4.9%) in women, but it was higher in people younger than 25 years (men 5.1%; 4.0% to 6.3%; women 6.2%; 5.2% to 7.8%). Prevalence was higher in the subgroup of younger women who were harder to engage in screening. The strongest determinant of chlamydial infection was having one or more new sexual partners in the past year.
Conclusions Postal chlamydia screening was feasible, but coverage was incomplete and uptake was modest. Lower coverage of postal screening in areas with more non-white residents along with poorer uptake in more deprived areas and among women at higher risk of infection could mean that screening leads to wider inequalities in sexual health.
Randomised trials show that systematic screening for genital Chlamydia trachomatis might reduce the incidence of pelvic inflammatory disease by about 50%.1 We investigated the coverage and uptake of systematic chlamydia screening by post, estimated prevalence of chlamydia, and explored factors associated with these measures.
Methods
The chlamydia screening studies (ClaSS) project has been described previously,2 and the full protocol is available at www.chlamydia.ac.uk.
We invited men and women aged 16-39, randomly selected from 27 general practices in the West Midlands and Avon, to collect their own specimens (urine in men, urine and vulvovaginal swab in women) and post them to us, and to complete a questionnaire on risk factors. Invitations and testing kits went to patients' registered address, and we confirmed residence at this address. We used postal reminders, telephone calls, home visits, and "flagging" of records at study practices to encourage participation.
Our colleagues in the reference laboratory (SS and AHe) used nucleic acid amplification tests to detect C trachomatis and confirmed positive results. Postal delays did not affect positivity rates (data not shown). Participants with chlamydia received results and treatment at their practice. Notification of partners was undertaken at either the practice or a genitourinary clinic. Statistical analyses of coverage of chlamydia screening (proportion receiving an invitation to be screened), uptake (proportion returning a specimen), and prevalence took into account clustering at the practice level and sampling probability.
Results
Of 19 773 people aged 16-39 who had been invited, we contacted 73% (14 382, see figure on bmj.com) successfully. Uptake of screening was 34.5% (95% confidence interval 31.2% to 38.0%) overall, and 31.5% (28.6% to 34.6%) in 16-24 year olds (table 1). After a single postal invitation, uptake was 22.2% (18.6% to 26.2%) in 16-24 year olds and was higher in women than men (table 1). A postal reminder and face to face contact (in a home visit, or "flagged" patients being invited to participate when they attended their practice) each increased uptake by around 5%. Screening coverage and uptake varied by practice (see table A on bmj.com). Coverage was lower in areas with higher proportions of residents from minority ethnic groups, and uptake was lower in practices with higher deprivation scores (see table B on bmj.com).
Table 1 Uptake of screening and prevalence of chlamydia according to effort needed to secure participation
The overall prevalence of chlamydia was 2.8% (2.2% to 3.4%) in men and 3.6% (3.1% to 4.9%) in women, but it was higher in people who were younger than 25 (men 5.1%, 4.0% to 6.3%), women 6.2%, 5.2% to 7.8%). Prevalence was below 1% in men older than 24 and women older than 29 years. Prevalence was higher among the subgroup of 16-24 year old women who only participated after repeated contacts (table 1). Having one or more new partners in the past 12 months was the strongest predictor of infection (table 2). The prevalence of chlamydia was also higher in single compared with married women and in men aged 20-24 than in people aged 16-19 years (tables C and D on bmj.com).
Table 2 Prevalence of infection according to number of sexual partners, and association between prevalence and sexual behaviour, in men and women
Prevalence did not vary substantially between practices (I2 = 34% of variation attributable to heterogeneity between practices, tables A, C, and D on bmj.com). We found weak evidence that chlamydia was more common in practices in more deprived areas (adjusted odds ratio for a 10 point increase in deprivation score, 1.2, 1.0 to 1.4, P = 0.077).
Discussion
Low N, Egger M. What should we do about screening for genital chlamydia? Int J Epidemiol 2002;31: 891-3.
Low N, McCarthy A, Macleod J, Salisbury C, Horner PJ, Roberts TE, et al. The chlamydia screening studies: rationale and design. Sex Transm Inf 2004;80: 342-8.
Andersen B, Olesen F, M?ller JK, ?stergaard L. Population-based strategies for outreach screening of urogenital Chlamydia trachomatis infections: a randomized, controlled trial. J Infect Dis 2002;185: 252-8.
Macleod J, Rowsell R, Horner P, Crowley T, Caul EO, Low N, Smith GD. Postal urine specimens: are they a feasible method for genital chlamydial infection screening? Br J Gen Pract 1999;49: 455-8.
Low N, Macleod J, Salisbury C, Egger M, and the ClaSS study group. Bias in chlamydia prevalence surveys. Lancet 2003;362: 1157-8.
Fenton KA, Korovessis C, Johnson AM, McCadden A, McManus S, Wellings K, et al. Sexual behaviour in Britain: reported sexually transmitted infections and prevalent genital Chlamydia trachomatis infection. Lancet 2001;358: 1851-4.
Low N, Sterne JAC, Barlow D. Inequalities in rates of gonorrhoea and chlamydia between black ethnic groups in south east London: cross sectional study. Sex Transm Inf 2001;77: 15-20.
Department of Health. Choosing health: making healthy choices easier. London: DoH, 2001.
?stergaard L, Andersen B, M?ller JK, Olesen F. Screening for klamydia med hjemmetest—en medicinsk teknologivurdering. Medicinsk Teknologivurdering—puljeprojekter 4(2). Copenhagen, Center for Evaluering og Medicinsk Teknologivurdering, 2002.
Salisbury C, Macleod J, Egger M, McCarthy A, Patel R, Holloway A, et al. Opportunistic or systematic screening for chlamydia? A study of consultations by young adults in general practice. Br J Gen Pract 2005 (in press).
((John Macleod, senior lecturer in primary)
Correspondence to J Macleod j.a.macleod@bham.ac.uk
Objective To measure the coverage and uptake of systematic postal screening for genital Chlamydia trachomatis and the prevalence of infection in the general population in the United Kingdom. To investigate factors associated with these measures.
Design Cross sectional survey of people randomly selected from general practice registers. Invitation to provide a specimen collected at home.
Setting England.
Participants 19 773 men and women aged 16-39 years invited to participate in screening.
Main outcome measures Coverage and uptake of screening; prevalence of chlamydia.
Results Coverage of chlamydia screening was 73% and was lower in areas with a higher proportion of non-white residents. Uptake in 16-24 year olds was 31.5% and was lower in men, younger adults, and practices in disadvantaged areas. Overall prevalence of chlamydia was 2.8% (95%confidence interval 2.2% to 3.4%) in men and 3.6% (3.1% to 4.9%) in women, but it was higher in people younger than 25 years (men 5.1%; 4.0% to 6.3%; women 6.2%; 5.2% to 7.8%). Prevalence was higher in the subgroup of younger women who were harder to engage in screening. The strongest determinant of chlamydial infection was having one or more new sexual partners in the past year.
Conclusions Postal chlamydia screening was feasible, but coverage was incomplete and uptake was modest. Lower coverage of postal screening in areas with more non-white residents along with poorer uptake in more deprived areas and among women at higher risk of infection could mean that screening leads to wider inequalities in sexual health.
Randomised trials show that systematic screening for genital Chlamydia trachomatis might reduce the incidence of pelvic inflammatory disease by about 50%.1 We investigated the coverage and uptake of systematic chlamydia screening by post, estimated prevalence of chlamydia, and explored factors associated with these measures.
Methods
The chlamydia screening studies (ClaSS) project has been described previously,2 and the full protocol is available at www.chlamydia.ac.uk.
We invited men and women aged 16-39, randomly selected from 27 general practices in the West Midlands and Avon, to collect their own specimens (urine in men, urine and vulvovaginal swab in women) and post them to us, and to complete a questionnaire on risk factors. Invitations and testing kits went to patients' registered address, and we confirmed residence at this address. We used postal reminders, telephone calls, home visits, and "flagging" of records at study practices to encourage participation.
Our colleagues in the reference laboratory (SS and AHe) used nucleic acid amplification tests to detect C trachomatis and confirmed positive results. Postal delays did not affect positivity rates (data not shown). Participants with chlamydia received results and treatment at their practice. Notification of partners was undertaken at either the practice or a genitourinary clinic. Statistical analyses of coverage of chlamydia screening (proportion receiving an invitation to be screened), uptake (proportion returning a specimen), and prevalence took into account clustering at the practice level and sampling probability.
Results
Of 19 773 people aged 16-39 who had been invited, we contacted 73% (14 382, see figure on bmj.com) successfully. Uptake of screening was 34.5% (95% confidence interval 31.2% to 38.0%) overall, and 31.5% (28.6% to 34.6%) in 16-24 year olds (table 1). After a single postal invitation, uptake was 22.2% (18.6% to 26.2%) in 16-24 year olds and was higher in women than men (table 1). A postal reminder and face to face contact (in a home visit, or "flagged" patients being invited to participate when they attended their practice) each increased uptake by around 5%. Screening coverage and uptake varied by practice (see table A on bmj.com). Coverage was lower in areas with higher proportions of residents from minority ethnic groups, and uptake was lower in practices with higher deprivation scores (see table B on bmj.com).
Table 1 Uptake of screening and prevalence of chlamydia according to effort needed to secure participation
The overall prevalence of chlamydia was 2.8% (2.2% to 3.4%) in men and 3.6% (3.1% to 4.9%) in women, but it was higher in people who were younger than 25 (men 5.1%, 4.0% to 6.3%), women 6.2%, 5.2% to 7.8%). Prevalence was below 1% in men older than 24 and women older than 29 years. Prevalence was higher among the subgroup of 16-24 year old women who only participated after repeated contacts (table 1). Having one or more new partners in the past 12 months was the strongest predictor of infection (table 2). The prevalence of chlamydia was also higher in single compared with married women and in men aged 20-24 than in people aged 16-19 years (tables C and D on bmj.com).
Table 2 Prevalence of infection according to number of sexual partners, and association between prevalence and sexual behaviour, in men and women
Prevalence did not vary substantially between practices (I2 = 34% of variation attributable to heterogeneity between practices, tables A, C, and D on bmj.com). We found weak evidence that chlamydia was more common in practices in more deprived areas (adjusted odds ratio for a 10 point increase in deprivation score, 1.2, 1.0 to 1.4, P = 0.077).
Discussion
Low N, Egger M. What should we do about screening for genital chlamydia? Int J Epidemiol 2002;31: 891-3.
Low N, McCarthy A, Macleod J, Salisbury C, Horner PJ, Roberts TE, et al. The chlamydia screening studies: rationale and design. Sex Transm Inf 2004;80: 342-8.
Andersen B, Olesen F, M?ller JK, ?stergaard L. Population-based strategies for outreach screening of urogenital Chlamydia trachomatis infections: a randomized, controlled trial. J Infect Dis 2002;185: 252-8.
Macleod J, Rowsell R, Horner P, Crowley T, Caul EO, Low N, Smith GD. Postal urine specimens: are they a feasible method for genital chlamydial infection screening? Br J Gen Pract 1999;49: 455-8.
Low N, Macleod J, Salisbury C, Egger M, and the ClaSS study group. Bias in chlamydia prevalence surveys. Lancet 2003;362: 1157-8.
Fenton KA, Korovessis C, Johnson AM, McCadden A, McManus S, Wellings K, et al. Sexual behaviour in Britain: reported sexually transmitted infections and prevalent genital Chlamydia trachomatis infection. Lancet 2001;358: 1851-4.
Low N, Sterne JAC, Barlow D. Inequalities in rates of gonorrhoea and chlamydia between black ethnic groups in south east London: cross sectional study. Sex Transm Inf 2001;77: 15-20.
Department of Health. Choosing health: making healthy choices easier. London: DoH, 2001.
?stergaard L, Andersen B, M?ller JK, Olesen F. Screening for klamydia med hjemmetest—en medicinsk teknologivurdering. Medicinsk Teknologivurdering—puljeprojekter 4(2). Copenhagen, Center for Evaluering og Medicinsk Teknologivurdering, 2002.
Salisbury C, Macleod J, Egger M, McCarthy A, Patel R, Holloway A, et al. Opportunistic or systematic screening for chlamydia? A study of consultations by young adults in general practice. Br J Gen Pract 2005 (in press).
((John Macleod, senior lecturer in primary)