| dc.description.abstract | o determine the sensitivity, specificity and positive predictive value of the
PSA test at the conventional cut-off value of 4 ng/ml.
Design: Retrospective study.
Setting: Nairobi Hospital Laboratory, Nairobi.
Data Source: Results of serum Prostate specific Antigen (PSA), estimation and prostate
histology specimens at the Nairobi Hospital Laboratory between January 1997 and
December 1999.
Results: A total of 3309 PSA tests and 524 prostate biopsies were processed during the
study period. One hundred cases had both PSA test and histology, where the PSA test
was done before the surgical procedure. Fourty nine of them had histological diagnosis
of cancer of prostate (CAP) while 71 had benign prostate hyperplasia (BPH). There
was considerable overlap in the PSA concentrations between the two groups, the ranges
being 0.34-36 ng/ml and 1.78-4339 ng/ml for BPH and CAP respectively. 63.4% of BPH
subjects had PSA concentrations above the 4 ng/ml threshold value; 29.6% being in
the diagnostic gray zone of 4-10 ng/ml. In contrast only 6% of CAP subjects had PSA
values in the gray zone. Using the 4 ng/ml cut-off, the sensitivity, specificity and positive
predictive value of the PSA test were 89.8, 37 and 49% respectively.
Conclusion: Although PSA is a sensitive test, it is not sufficiently specific to discriminate
between BPH and CAP at intermediate values. Additional approaches are required | en |
