The benefit of negative tests in non-ulcer dyspepsia.
OBJECTIVE
Negative diagnostic tests are usually evaluated by their ability to advance a diagnostic search, or they are considered redundant expenditures in establishing a definitive diagnosis. It has remained difficult to assess their benefit in terms of their own merit and the reassurance that they provide to a patient. The aim of the present study is to develop a mathematical model for quantifying the impact of diagnostic tests on a patient's health-related quality of life (HRQL).


METHODS
An influence diagram is used to model how non-ulcer dyspepsia (NUD) and its medical care affect HRQL. Diagnostic tests and medical therapy benefit HRQL by alleviating fear of disease and NUD symptoms. Medical care can also adversely affect HRQL, lead to expenses in time and money, and compromise a patient's sense of autonomy. HRQL is modeled as the focal point of multiple influences detracting from its value.


RESULTS
Negative diagnostic tests can improve HRQL in NUD. The improvement of HRQL by diagnostic tests depends on a multitude of individual influences and the interactions between them, such as the severity of NUD symptoms andfear of disease, as well as the impact of medical care itself on HRQL. If a patient harbors a strong fear of serious disease or cancer, more extensive testing is likely to improve the patient's well-being and appears a worthwhile endeavor. Other patients, however, would be served perfectly well by empirical therapy only. For the vast majority of subjects with NUD who never seek medical advice, the unpleasantness of the disease itself does not outweigh the anticipated downside of obtaining medical care.


CONCLUSIONS
The analysis illustrates the applicability of the influence diagram in modeling disease behavior. This method helps to assess the benefit of negative tests beyond their means of generating information.
Sonnenberg
Amnon
A
Department of Veterans Affairs Medical Center, Albuquerque, New Mexico 87108, USA. sonnbrg@unm.edu
Vakil
Nimish
N
D001294:Attitude to Health; D004415:Dyspepsia / Q000175:diagnosis* / Q000523:psychology; D005773:Gastroscopy / Q000523:psychology; D006801:Humans; D011788:Quality of Life