Item 3.    Describe the study population: The inclusion and exclusion criteria, setting and locations where data were collected.

Example

Patient population. Female patients attending participating family planning clinics in the states of Washington and Oregon during 1992 and 1993 were considered for enrollment in the study. The previously published screening criteria of the Region X Chlamydia Project were used to establish eligibility for enrollment.[ref] These criteria included any of the following: (i) mucopurulent cervicitis, pelvic inflammatory disease, friable cervix, or abnormal bleeding; (ii) a partner with signs and/or symptoms suggestive of urethritis; (iii) client request; (iv) rape within the previous 60 days; (v) candidacy for intrauterine device insertion; and (vi) a positive pregnancy test and a bimanual pelvic examination. Alternatively, the criteria included two or more of the following: (i) age under 24 years and being sexually active; (ii) new sex partner in the previous 60 days; (iii) sex partner with multiple partners in the previous 30 days; (iv) multiple sex partners in the previous 30 days; and (v) use of nonbarrier birth control method or no birth control method (nonbarrier birth control methods include oral contraceptives, the intrauterine device, sterilization, and all natural family planning methods) [1]

Since diagnostic accuracy describes the behavior of a test under particular circumstances, a report of the study must also include a helpful description of the targeted population. The eligibility criteria describe the targeted patient population, including additional exclusion criteria used for reasons of safety or feasibility.

Readers must know whether or not the study excluded patients with a specific condition known to adversely affect the way the test works, which would inflate diagnostic accuracy (limited challenge bias).[2] Examples are the exclusion of patients using beta-blockers in studies of exercise electrocardiography and the exclusion of patients with pre-existing pulmonary diseases in studies of ventilation-perfusion scintigraphy.[3,4]

Tests may perform differently in a primary care setting than in a secondary or tertiary care setting. Test performance may differ if the test is used for screening rather than for confirmation of diagnostic suspicion. The spectrum of the target disease as well as the range of other conditions that occur in patients suspected of the target disease can vary from setting to setting, depending on what referral mechanisms were in play.[5,6,7] For these reasons, the report should include a careful description of where patients were recruited and where the test and the reference standard were performed.

References