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Table 3. Summary of benefits and harms of screening 1000 high-risk pregnant
women for bacterial vaginosis1
| Benefit
and relevant factors |
"General"
high-risk groupa |
"More
selected" high-risk groupb |
| Assumptions |
| Proportion
of pregnant women who meet screening criteria |
0.1 |
0.03 |
| Prevalence
of BV in population |
0.25 |
0.25 |
| Relative
risk of PTD in BV patients |
1.6 |
1.6 |
| Sensitivity
of screening test |
0.95 |
0.95 |
| Specificity
of screening test |
0.95 |
0.95 |
| Adherence
to treatment |
0.8 |
0.8 |
| Effect
sizes, BV patients (probability: control group vs treated group [CI])c |
| PTD
<37 weeks |
-0.075(-0.19
to +0.04) |
+0.22(+0.13
to +0.31) |
| PPROM |
-0.04(-0.101
to +0.03) |
+0.29(+0.15
to +0.43) |
| PTD
<34 weeks |
+0.012(-0.06
to 0.08) |
+0.06(+0.01
to +0.15) |
| Effect
sizes, patients without BV (probability: control group vs treated group)c |
| PTD
<37 weeks |
0 |
0 |
| PPROM |
0 |
0 |
| PTD
<34 weeks |
-0.02 |
-0.06 |
| Results
(n) |
| Patients
with unsuspected BV |
250 |
250 |
| Correctly
diagnosed with BV |
238 |
238 |
| BV
patients who complete therapy |
190 |
190 |
| BV
patients with missed diagnosis |
13 |
13 |
| Incorrectly
diagnosed with BV |
38 |
38 |
| Outcomesc |
| Decrease
or increase in PTD <37 weeks (CI) |
-14(-36
to +7) |
+42(+25
to +59) |
| Decrease
or increase in PPROM |
-8(-19
to +4) |
+49(+28
to +70) |
| Decrease
or increase in PTD <34 weeks |
+2(-11
to +14) |
+9(-2
to +19) |
a Screen all women who have at least one previous
PTD.
b Screen if there is more than one previous
PTD or other risk factors.
c Minus sign indicates a net increase, plus
indicates a net decrease, in adverse effects.
1 BV, bacterial vaginosis; PTD, preterm delivery;
CI, confidence interval; PPROM, preterm premature rupture of membranes. |
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