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Public health issues

Screening in men

Chlamydial infections are asymptomatic in approximately 30 - 50% of infected men. It is generally assumed [more data needed] that asymptomatic infection, like symptomatic infection, is infectious. From an epidemiological perspective it is therefore important to reduce the reservoir of asymptomatic infection in the community. Significant costs are associated with screening for asymptomatic infection but these have to be balanced against the significant costs to health services of failing to identify sources of infection. Screening strategies need to be adapted to local and national epidemiological and financial circumstances. This review focuses on recent studies in selected population groups.

Males

Adolescent males are at high risk of acquiring chlamydial genital tract infection and are the major source of infection for young sexually active women. Furthermore epididymitis is associated with chlamydial infection and may lead to sterility, though adequate research data are lacking.

Randolph & Washington, 1990 used a decision analysis model to evaluate the direct medical costs [only] in a hypothetical cohort of 1000 males and their female partners of three different screening strategies: leukocyte esterase dipstick, direct smear fluorescent antibody and tissue culture. Costs per cure were: leukocyte esterase US$51, direct smear $192 and culture $414.  Compared with direct smear it was estimated that the dipstick test saved over $9,727 per cohort of 1,000 sexually active adolescent males screened. Sensitivity analyses were performed. Leukocyte esterase (LE) was not a good screening strategy in that it only resulted in lower overall costs per cohort compared with no screening at high prevalences above 21%.

A similar study by Genc et al., 1993 evaluated both direct and indirect medical costs in 1000 adolescent males and their partners, using two decision analysis models. They explored the impact of enzyme immunoassay chlamydial antigen detection (EIA) on all male urines, or on leukocyte esterase positive urines only compared with no screening. Compared with no screening, the LE-EIA and EIA screening strategies reduced the overall costs when the prevalence of chlamydial infection in males exceeded 2% and 10%, respectively. EIA screening of all urines improved cure rates by some 12.2% to 12.6% (95% confidence intervals) but reduced incremental savings by at least $2144 per cured male compared  with EIA screening of LE positive urines only. As far as antibiotic treatment was concerned, a single oral dose of azithromycin improved the cure rates of both screening strategies by 12 - 16% compared with a 7 day course of doxycycline., while reducing overall costs by  5 - 9%. However economic comparison was made difficult by the author's failure to include the incremental cost effectiveness ratios for these treatment strategies [Malek & Malik, 1999].

Ginocchio et al., 2003 used a decision analysis model to compare the clinical and economic consequences of three strategies: no screening; screening all male urines with the ligase chain reaction [LCR]  technique or  prescreening urines with LE dipstick confirming only LE positives with LCR. At a chlamydial prevalence of 5%, the no screening cost was US$ 7.44 per man screened, resulting in an expected 522 cases of pelvic inflammatory disease  in their female partners per 100000 men. LE-LCR was the most cost-effective strategy, preventing 242 of these cases of pelvic inflammatory disease at an additional cost of $ 29.14 per man screened. Screening all male urines by LCR strategy prevented 104 further  cases of pelvic inflammatory disease than screening the LE positive urines only, but it cost $ 22.62 more per male screened. However were the LCR assay cost to decline to < $18 this would be the more efficient strategy.  [NB. The LCR test is now obsolete, but the study is relevant in that other nucleic acid amplification based tests have comparable or better performance].

[MEW] July 2004

NEXT: Females

References

Genc, M., Ruusuvaara, L. & Mardh, P. A. (1993). An economic evaluation of screening for Chlamydia trachomatis in adolescent males. JAMA 270, 2057 - 2064.

Ginocchio, R. H., Veenstra, D. L., Connell, F. A. & Marrazzo, J. M. (2003). The clinical and economic consequences of screening young men for genital chlamydial infection. Sexually Transmitted Diseases 30, 99 - 106.

Howell, M. R., Kassler, W. J. & Haddix, A. (1997). Partner notification to prevent pelvic inflammatory disease in women. Cost-effectiveness of two strategies. Sexually Transmitted Diseases 24, 287 - 292.

Malek, M. & Malik, F. (2001). Economic implications of Chlamydia trachomatis. In: International handbook of Chlamydia [ed. Moss, T. R.] pp 97 - 113. Euromed Publications Ltd., Haslemere UK, ISBN 1 899015 43 4 [Good review].

Randolph, A. G. & Washington, A. E. (1990). Screening for Chlamydia trachomatis in adolescent males: a cost-based decision analysis. American Journal of Public Health 80, 545 - 550.