Table 6.
Circumstances/conditions when screening might be appropriate or contra-indicated.
| Circumstances favoring screening | Circumstances when screening not appropriate |
|---|---|
| Disease constitutes a significant public health problem, meaning that it is a relatively common condition with significant morbidity and mortality or disease is contagious and might infect others before symptoms occur and disease detected. | Disease is rare or not serious or, if serious there is no effective treatment for disease. |
| The population to be screened can be so defined that the prevalence is high and there are no significant co-morbidities. | Unknown or low population prevalence |
| Treatment before symptoms occur is more effective than if treatment is delayed | No benefit to early treatment and/or significant likelihood of overdiagnosis (pseudodisease) |
| “Gold Standard” diagnostic exists and screening test sensitivity and specificity is high and based on adequate sample size | Screening test data is based on small sample sizes or is difficult to extrapolate to larger pool of screening centers with high sensitivity and specificity (e.g. high inter-observer variability) |
| Consequences of false negative or false positives are modest | Consequences of one or more of these errors significant |
| Screening test is inexpensive, easy to administer, not harmful and reliable | Any of these circumstances not met |
| There must be some mechanism for follow-up of subjects with positive screening results to ensure subsequent diagnostic testing and ultimate treatment takes place. |