CTF Structured Abstract: Papillomavirus

Canadian Task Force on Preventive Health Care

Structured Abstract

Periodic health examination, 1995 update: 1. Screening for human papillomavirus infection in asymptomatic women

Ken Johnson, MD

Objective
Burden of Suffering
Options
Outcomes

Evidence
Values
Benefits, Harms, and Costs
Recommendations

Validation
Sponsors
Selected References

Objective

To develop recommendations for practising physicians on the advisability of screening for human papillomavirus (HPV) infection in asymptomatic women.

Burden of Suffering

In Canada in 1993 approximately 1300 new cases of invasive cervical cancer were diagnosed, and about 400 deaths were expected to occur from this disease. In the United States an estimated 13 000 new cases of cervical cancer are diagnosed every year, with about 7000 deaths annually from prevalent disease. In Canada the yearly overall cost of invasive disease and death from cervical cancer has been estimated at $180 to $270 million.

Many of the epidemiologic features of HPV infection remain to be determined, and precise estimates of the incidence, prevalence and natural history of this infection are unavailable. Cases of condylomata acuminata (proliferative HPV infection) are reportable in Britain, where it is the most frequently diagnosed viral sexually transmitted disease (STD). Data from STD clinics in Britain and Australia indicate a prevalence of 4% to 13% among clinic attendees. These data, however, are based on visible condylomata and consequently underestimate the true prevalence of HPV infection, since this condition is commonly subclinical. It has been estimated that about 10% of people infected with HPV have visible lesions, 20% have lesions demonstrable with the use of colposcopy or a magnifying lens, and 70% have subclinical infection. Subclinical infection can be detected only through clinical or laboratory testing, including Papanicolaou smears.

Options

Visual inspection, Papanicolaou testing, colposcopy or cervicography, use of HPV group-specific antigen, DNA hybridization, dot blot technique, Southern blot technique or polymerase chain reaction followed by physical or chemical therapeutic intervention

Outcomes

Evidence for a link between HPV infection and cervical cancer, sensitivity and specificity of HPV screening techniques, effectiveness of treatments for HPV infection, and the social and economic costs incurred by screening.

Evidence

MEDLINE was searched for articles published between January 1966 to June 1993 with the use of the key words "papillomavirus," "cervix neoplasms," "mass screening," "prospective studies," "prevalence," "sensitivity," "specificity," "human" and "female." Studies were selected and evaluated to determine the epidemiologic features and natural history of HPV infection, the relation between HPV infection and cervical cancer, and the effectiveness of diagnostic and therapeutic intervention.

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.

Benefits, Harms, and Costs

Potential benefits are to prevent cervical cancer and eliminate HPV infection.

Although Papanicolaou testing alone has few adverse effects apart from usually minor discomfort, the need for repeat testing, colposcopy, various destructive therapies and possible surgery may have a negative impact on the individual. Most people with HPV infection are probably asymptomatic, and diagnosis of HPV infection may produce a significant labelling of otherwise healthy people as patients with a sexually transmitted disease, for which therapy is generally ineffective. Although it may be in a dormant state for many months or years, considerable distress may follow once an otherwise healthy person becomes a "patient."

A significant increase in the number of Papanicolaou smears and referrals for colposcopy (on a population basis) would result in large financial and other costs to society, including the increased depletion of resources to deal with the necessary testing and treatment.

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 exclude HPV screening (beyond Papanicolaou testing for cervical cancer) using any of the following diagnostic tests: visual inspection, papanicolaou testing, colposcopy or cervicography, group-specific antigen, in-situ DNA hybridization, dot blot technique, southern blot technique, PCR [D, I, II-2, III]

Validation

This report was externally peer reviewed. Attendees at a national workshop on screening for cervical cancer, held in Ottawa Nov. 27 to 29, 1989, concluded that there was insufficient evidence to add specific tests for HPV infection to routine screening for cervical cancer. Like the Canadian task force, the US Preventive Services Task Force has made no specific recommendations regarding screening for HPV infection separate from the recommendations for cervical cancer screening.

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.