|
.gif)
|
|
The FemExam kit is
a rapid, objective, and easy to use method for the diagnosis of
bacterial vaginosis in women with vaginal discharge.
Evaluation of a new
rapid diagnostic kit (FemExam) for bacterial vaginosis in patients with
vaginal discharge syndrome in The Gambia.
West B, Morison L, Van Der Loeff MS, Gooding
E, Awasana AA, Demba E, Mayaud P.
Sexually
Transmitted Diseases 2003;30:483-489
Summary:
Question
What are the performances of the commercial FemExam card test and a
simplified version of the Amsel clinical criteria compared to the Nugent
Gram stain scoring system for the diagnosis of bacterial vaginosis (BV) in
Gambian women with vaginal discharge?
Design
The results of the FemExam assay, using either or both of the two test
cards, were compared to those of a simplified version of the Amsel
clinical criteria and the Nugent Gram stain score for the detection of BV
in women with symptoms of vaginal discharge attending a genitourinary
medicine clinic in The Gambia.
Participants
Two hundred nineteen consecutive women between 18 and 50 years old (mean =
26 years) with symptoms of vaginal discharge and/or vaginal itching
attending a genitourinary medicine clinic in Fajara, The Gambia, were
tested. Women younger than 18 years, pregnant, with advanced HIV disease,
or with bloody discharge were excluded. Eighty-four percent and 11% of
women reported having one and zero sex partners, respectively, in the past
3 months. Seventy one percent of women were married; 3% were commercial
sex workers. Antibiotic use was reported by 18%. Thirty-eight percent
douched before sex and 89% after sex.
Description of Tests and Diagnostic
Standard
During a speculum examination, five vaginal swabs were collected in the
same order from each woman and used for 1) culture, 2) wet prep, 3) pH
measurement and Gram stain, 4) FemExam card 1, and 5) FemExam card 2. The
FemExam (Litmus Concepts, Santa Clara, CA) is a commercial, rapid
diagnostic test for BV that consists of two plastic cards. Card 1 measures
vaginal fluid pH and the presence of trimethylamine, and Card 2 measures
proline iminopeptidase activity of G. vaginalis. Women were
considered positive for BV by the FemExam method if both tests were
positive on Card 1, if the Card 2 test was positive, or if 2 of 3 tests
were positive on both cards. The women were evaluated for BV using the
conventional Amsel clinical criteria and a simplified definition in which
any abnormal discharge was considered as one positive criterion,
regardless of the discharge characteristics. BV was diagnosed on the basis
of a Nugent Gram stain score of > 7. The cost per patient and cost per
true case for each method were calculated using the total cost incurred by
the health system in applying a diagnostic test and treating those with a
positive test divided by the number of patients evaluated and by the
number of true cases detected, respectively
Main Outcome Measures
The sensitivity, specificity, positive predictive value (PPV), and
negative predictive value (NPV) of the simplified Amsel criteria and three
interpretations of the FemExam results for the diagnosis of BV as
determined by the Nugent score were calculated.
Main Results
The prevalence of BV according to the Nugent score was 47.9%. The
performances of the Amsel simplified criteria and the three FemExam test
card combinations in comparison with the Nugent score of >7 for
the diagnosis BV are shown in Table 1. In the analyses, the denominators
vary because not all data were correctly recorded for all 219 women. The
costs for each method based on the prevalence of BV in this population are
shown in Table 2.
Authors' Conclusions
The FemExam test compared favorably with
conventional clinical diagnosis and has the advantage of being rapid, less
subjective, and easily performed in clinical settings of resource-poor
countries. Presumptive treatment of BV in settings with a high prevalence
of BV is at present more core-effective than any current diagnostic
method.
Source of funding: Litmus Concepts,
Inc., Palo Alto, CA, and the World Health Organization, Division of
Sexually Transmitted Infections, Geneva.
For correspondence: Beryl West, MRC
Laboratories, Fajara, P.O. Box 273, Banjul, The Gambia. E-mail address:
beryl_west@hotmail.com.
|
