CTF Structured Abstract: Chlamydia

Canadian Task Force on Preventive Health Care

Structured Abstract

Periodic health examination, 1996 update: 2. Screening for chlamydial infections

H. Dele Davies, MD, MSc, FRCPC, Assistant Professor, Departments of Microbiology, Infectious Diseases and Pediatrics, University of Calgary; Elaine E.L. Wang, MD, MSc, FRCPC, Associate Professor, Department of Pediatrics, University of Toronto, Head, Division of Clinical Epidemiology, Hospital for Sick Children, Toronto

Objective
Burden of Suffering
Options
Outcomes

Evidence
Values
Benefits, Harms, and Costs
Recommendations

Validation
Sponsors
Selected References

Objective

To update the 1984 recommendations of the Canadian Task Force on the Periodic Health Examination on the routine screening of asymptomatic patients for infection with Chlamydia trachomatis.

Burden of Suffering

Infection with C. trachomatis is the most common sexually transmitted disease (STD) in North America, causing infection in two to three times more people than Neisseria gonorrhoeae. In Canada, the incidence rate of C. trachomatis infection is estimated to be 216 per 100 000 people per year. Although there are no Canadian estimates of the associated cost of infection, in the United States there are more than 4 million infections each year, with an estimated cost in 1990 of $2.2 billion (US). Most infections (60% to 80%) among women are asymptomatic, but the spectrum of symptoms includes mucopurulent cervicitis, endometritis, salpingitis, postabortal pelvic sepsis and perihepatitis. Among men, the spectrum of symptoms caused by C. trachomatis includes urethritis, epididymitis and conjunctivitis.

Options

Screening, with the use of culture or nonculture tests, of the general population, of certain high-risk groups or of all pregnant women; or no routine screening.

Outcomes

Rates of asymptomatic and symptomatic chlamydial infection, perinatal complications, long-term complications of infection (i.e., pelvic inflammatory disease, infertility and ectopic pregnancy), coinfection with other sexually transmitted diseases, disease spread, hospital care, complications of therapy and costs of infection and of screening.

Evidence

A MEDLINE search of articles published from Jan. 1, 1983, to Dec. 31, 1995, was conducted by exploding the major MeSH heading chlamydial infections with the subheadings complications, diagnosis, drug therapy, economics, cost, epidemiology, etiology, history, microbiology, mortality, mass screening, prevention and control, therapy and transmission.

Recommendations were graded as:

A Good evidence to support the recommendation that the condition be specifically considered in a PHE.

B Fair evidence to support the recommendation that the condition be specifically considered in a PHE.

C Poor evidence regarding inclusion or exclusion of the condition in a PHE, but recommendations may be made on other grounds.

D Fair evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

E Good evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

Quality of evidence was rated according to 5 levels:

I Evidence from at least 1 properly randomized controlled trial (RCT).

II-1 Evidence from well-designed controlled trials without randomization.

II-2 Evidence from well-designed cohort or case-control analytic studies, preferably from more than 1 centre or research group.

II-3 Evidence from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments could also be included here.

III Opinions of respected authorities, based on clinical experience, descriptive studies or reports of expert committees.

Values

The 13-member Task Force of experts in family medicine, geriatric medicine, pediatrics, psychiatry and epidemiology used an evidence-based method for evaluating the effectiveness of preventive health care interventions. Recommendations were not based on cost-effectiveness of options. Patient preferences were not discussed.

Background papers providing critical appraisal of the evidence and tentative recommendations prepared by the chapter author were pre-circulated to the members. Evidence for this topic was presented and deliberated upon in 1- to 2-day meetings. Consensus was reached on final recommendations.

Advice from reviewers and experts and recommendations of other organizations were taken into consideration. Prevention of symptomatic disease and decreased overall costs were given high values.

Benefits, Harms, and Costs

The greatest potential benefits of screening asymptomatic patients for chlamydial infections are the prevention of complications, especially infertility and perinatal complications, and the prevention of disease spread. There is no evidence that screening of the general population for chlamydial infections leads to a reduction in complications, and screening may increase costs. However, there is evidence that annual screening of selected high-risk groups and of pregnant women during the first trimester is beneficial in preventing symptoms and reducing the overall cost resulting from infection.

Recommendations

Recommendation grade [A, B, C, D, E] and level of evidence [I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations in support of individual recommendations are identified in the guideline text.

There is fair evidence to support screening of pregnant women during their first prenatal visit and subsequent treatment [B, II-2]
There is fair evidence to support annual screening of high-risk groups [B, I, II-2]
There is fair evidence to exclude routine screening of the general population [D]

Validation

This report was externally reviewed. These recommendations are similar to those of the US Preventive Services Task Force and the US Centers for Disease Control and Prevention.

A	Good evidence to support the recommendation that the condition be specifically considered in a PHE.
B	Fair evidence to support the recommendation that the condition be specifically considered in a PHE.
C	Poor evidence regarding inclusion or exclusion of the condition in a PHE, but recommendations may be made on other grounds.
D	Fair evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.
E	Good evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

I	Evidence from at least 1 properly randomized controlled trial (RCT).
II-1	Evidence from well-designed controlled trials without randomization.
II-2	Evidence from well-designed cohort or case-control analytic studies, preferably from more than 1 centre or research group.
II-3	Evidence from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments could also be included here.
III	Opinions of respected authorities, based on clinical experience, descriptive studies or reports of expert committees.