Diagnostic research in benign prostatic hyperplasia--from sensitivity to neural networks

Performance of the rapid plasma reagin and the rapid syphilis screening tests in the diagnosis of syphilis in field conditions in rural Africa

OBJECTIVES

To assess the rapid plasma reagin (RPR) test performance in the field and to evaluate a new rapid syphilis test (RST) as a primary screen for syphilis.

METHODS

1325 women of reproductive age from rural communities in the Gambia were tested for syphilis seropositivity using a RPR 18 mm circle card and a RST strip. Within 1 week a repeat RPR and a TPHA test were carried out using standard techniques in the laboratory.

RESULTS

Comparing field tests to a diagnosis of "active" syphilis defined as laboratory RPR and TPHA positive, the RPR test was 77.5% sensitive and 94.1% specific; the RST was 75.0% sensitive and 95.2% specific. The RST was easier to use and interpret than the RPR test especially where field conditions were difficult. In this setting with a low prevalence of syphilis in the community (3%), the chance of someone with a positive test being confirmed as having serologically active syphilis was less than 50% for both tests.

CONCLUSIONS

The appropriateness of syphilis screening using RPR testing in antenatal clinics and health centres should be questioned if there is a low prevalence in the population, conditions for testing are poor, and resources limited. There is still an urgent need for an appropriate rapid syphilis test for field use.

Variability of pressure-flow studies in men with lower urinary tract symptoms

The objective of this study was to assess the short-term test-retest variability of pressure-flow studies (PFS) in men with lower urinary tract symptoms (LUTS). By choosing a short interval between two consecutive PFS, but notably not performing two tests within a single session, both tests represent the same routine testing procedure. Eighty-nine patients with LUTS suggestive of bladder outlet obstruction or detrusor underactivity, who received PFS, were asked to undergo a second urodynamic evaluation within 4 weeks after the initial test. At both visits, specialized physicians performed the PFS. Obstruction was quantified using the Abrams-Griffiths number (AG number). Each patient was classified as obstructed, unobstructed, or equivocally obstructed according to the International Continence Society nomogram. As expected, no systematic difference was observed in AG number between the first and the second visit at the group level. There was, however, considerable variation at the individual level. The average within-patient standard deviation was 14 cm H(2)O. This finding shows that if a patient's AG number is 30 at the first visit, his true AG number can be any value between 30 +/- 1.96 * 14 = 3 to 57, owing to random variability alone. The average within-patient standard deviation did not differ significantly between sub-groups of obstruction and other variables such as patient age, symptom score, prostate volume, or residual volume. The variability appeared to increase slightly with an increased interval between visits. Of all patients, 39% changed at least one category of obstruction at the second visit and 3% changed from definitely obstructed to definitely unobstructed or vice versa. We conclude that PFS cannot stand the test of serving as a gold standard to identify bladder outlet obstruction in patients with LUTS.