False-negative results in screening programmes: systematic review of impact and implications.
When assessing whether a screening programme is appropriate, there is a particular obligation to ensure that the harms as well as the benefits are considered. Among these harms is the likelihood that false-negative results will occur. In some cases, the consequences of these can be difficult to assess, although false reassurance leading to diagnostic delay and subsequent treatment has been suggested. However, no test is totally accurate (with 100% sensitivity and specificity), and false-negative results are inherent in any screening programme that does not have 100% sensitivity. This review was carried out to assess the medical, psychological, economic and legal consequences of false-negative results that occur in national screening programmes. (1) to determine the consequences of false-negative findings; (2) to investigate how their adverse effects can be minimised; to assess their implications for the NHS, including the impact of false-negatives on public confidence in screening programmes; to identify relevant theoretical perspectives that may be potentially useful when considering the implications of false-negative results. A systematic literature review was carried out. This included a search of 18 electronic databases, various bibliographies and contact with experts to identify relevant literature and perspectives. Outcomes included in the review fell into four categories: medical outcomes (morbidity and mortality); psychological outcomes (distress, false reassurance, loss of confidence in services); economic outcomes (such as costs to the NHS); legal outcomes (such as litigation). Other outcomes, such as the impact of false-negatives on public confidence in screening programmes, were also included. The participants included individuals taking part in screening programmes, healthcare professionals and organisations responsible for screening programmes. Methodological details of the review are provided in the full report. A total of 6660 abstracts were screened, and 420 potentially relevant papers were identified. Most of the studies that were identified presented only anecdotal evidence. (1) Medical outcomes: In all, 13 papers presented quantitative information relevant to the medical consequences of false-negative results; seven of these were primary studies, and the remaining studies were literature reviews or models examining the likely impact of false-negative results. (2) Psychological outcomes: A total of eight published studies presented information on the psychological consequences of negative results in general; only one study, on antenatal screening, provided direct evidence of the psychological consequences of false-negative results, where they were associated with lower parental acceptance of the affected child and with blaming others for this outcome. (3) Economic outcomes: Only two studies presented information on the economic consequences. The strength of evidence from most of the primary studies was low. There is some evidence that false-negative results may have a large legal impact. For example, in cervical screening they have led to legal action and its associated costs, including payment of compensation; this is based on reports of events in both the UK and US health systems. There also seems to be a consensus in the literature that false-negatives may have a negative impact on public confidence in screening; evidence is again limited however. False-negatives are evident in all screening programmes, even when the quality of the service provided is high. They may have the potential to delay the detection of breast and cervical cancer, but there is little evidence to help assess their psychological consequences in these or other screening programmes. False-negatives are likely to lead to legal action being taken by those individuals affected, and potentially may reduce public confidence in screening. (ABSTRACT TRUNCATED)