Table 3.
Studies that investigated subgroup variations*
| Study, Year | Approach to the analysis of spectrum bias/effect | Disease (number of subjects) | Diagnostic or screening test | Factors investigated | Effect on sensitivity and/or specificity | Effect on Likelihood ratios |
| Van der schouw, 1995 [5] | Subgroup analysis | Epididymitis (372) | Ultrasonography | Disease prevalence (severity according to clinician) | Disease prevalence (severity according to clinician) | Disease prevalence (severity according to clinician) |
| Morise, 1995 [36] | Subgroup analysis | Coronary disease (4467) | Exercise electrocardiography | Sex Verification by the gold standard (angiography) or not | Sex Verification bias by the gold standard (angiography) or not | Not considered |
| O'Connor, 1996 [6] | Subgroup analysis | Multiple sclerosis (303) | Magnetic resonance imaging and evoked potentials | Study group (two pooled studies considered), disease prevalence, clinical subjective disease probability | Study group, disease prevalence, clinical subjective disease probability | Not considered |
| Egglin, 1996 [37] | Subgroup analysis | Pulmonary embolism (24) | Pulmonary arteriogram | Disease prevalence | Disease prevalence | Not considered |
| Roger, 1997 [8] | Subgroup analysis | Coronary disease (3679) | Exercise echocardiography | Sex | Sex | Not considered |
| Curtin, 1997 [7] | Subgroup analysis | Obesity (226) | Body mass index | Weight, sex | Weight, sex | Not considered |
| Moons, 1997 [9] | Subgroup analysis and modelling of sensitivity | Coronary disease (295) | Exercise test | Patient history and clinical examination, various disease-related factors (maximal load, relative load, systolic blood pressure, number of diseased vessels) | Sex, expected load, maximal load, relative load, systolic blood pressure (baseline and peak), number of diseased vessels | Age, sex, symptoms, smoking, beta blocker use, cholesterol level, expected load, maximal load, relative load, systolic blood pressure (baseline and peak) |
| Santana-Bodao, 1998 [38] | Subgroup analysis | Coronary disease (702) | Single-photon emission computed tomography | Sex | Sex | Not considered |
| Steinbauer, 1998 [10] | Subgroup analysis | Alcohol abuse (1333) | Various screening tests | Race and sex | Race and sex | Race and sex |
| DiMatteo, 2001 [39] | Subgroup analysis | Group A beta haemolytic streptococcal pharyngitis (498) | Rapid antigen detection test | Disease severity | Disease severity | Not considered |
| Filly, 2002 [48] | Subgroup analysis and modelling | Cirrhosis (100) | Nodularity of surfaces of the liver | Deep versus superficial surfaces | Deep versus superficial surfaces | Age, sex, pathological type of cirrhosis |
| Hall, 2004 [40] | Subgroup analysis and modelling | Group A beta haemolytic streptococcal pharyngitis (561) | Rapid antigen detection test | Disease severity | Disease severity | Not considered |
| Meideros, 2005 [49] | Subgroup analysis | Glaucoma (136) | Scanning laser polarimetry | Two forms of glaucomatous optic neuropathy | Two forms of glaucomatous optic neuropathy | Two forms of glaucomatous optic neuropathy |
* Papers published between 1978 and 2000 were identified from the systematic review by Whiting et al [14]. Papers published between 2000 and 2005 were similarly selected through Medline® using the keywords: diagnostic, test, screening, performance, accuracy, sensitivity, specificity, likelihood ratio, spectrum, subgroup, bias, prevalence, accuracy. Only primary studies investigating variations in diagnostic test performances between subgroups were considered. Letters were excluded.