Ross et al developed a risk scoring system based on logistic regression to identify women at risk for preterm delivery. 22 factors based on historical or current gestational data were identified as significant. Women may be identified based on a logistic score or number of risk factors present.
Patient population:
(1) Involved 8,240 patients delivering at Harbor/UCLA Medical Center in Los Angeles.
(2) The population was predominantly Hispanic.
(3) Data was collected from July, 1979 to December 1982.
|
Historic Factor |
Univariate Odds Ratio |
Logistic Odds Ratio |
Regression Coefficient |
|---|---|---|---|
|
previous induced abortion |
1.64 |
1.309 |
0.269 |
|
habitual abortions |
3.31 |
2.210 |
0.793 |
|
previous premature delivery |
3.09 |
2.488 |
0.912 |
|
previous neonatal death |
2.19 |
1.277 |
0.244 |
|
uterocervical anomaly |
5.26 |
1.489 |
0.398 |
|
classic Caesarean section |
2.11 |
1.600 |
0.470 |
|
previous myomectomy |
46.0 |
22.847 |
3.130 |
|
chronic hypertension |
2.60 |
1.799 |
0.587 |
|
previous urinary tract infection |
1.38 |
1.107 |
0.101 |
|
renal disease |
2.38 |
2.115 |
0.749 |
|
psychiatric hospitalization |
2.41 |
1.380 |
0.322 |
|
cigarette abuse |
1.78 |
1.374 |
0.318 |
|
marijuana abuse |
3.30 |
2.072 |
0.728 |
|
narcotic abuse |
5.58 |
1.905 |
0.645 |
from Table 2, page 342
|
Current Gestation (Developing) Factor |
Univariate Odds Ratio |
Logistic Odds Ratio |
Regression Coefficient |
|---|---|---|---|
|
size-date discrepancy |
1.46 |
1.393 |
0.331 |
|
severe anemia |
2.51 |
2.165 |
0.772 |
|
threatened abortion |
4.30 |
4.134 |
1.420 |
|
incompetent cervix |
24.34 |
12.527 |
2.528 |
|
surgery requiring hospitalization |
2.20 |
1.900 |
0.642 |
|
multiple gestation |
9.44 |
6.755 |
1.190 |
|
pre-eclampsia, mild |
2.37 |
1.705 |
0.534 |
|
bleeding after 20 weeks |
5.89 |
5.321 |
1.672 |
from Table 2, page 342
logistic score =
= SUM(regression coefficients for historic factors present) + SUM(regression coefficients for developing factors present) + (constant )
where:
• constant = -3.193
number of risk factors =
= SUM(individual risk factors present)
Interpretation:
• minimum score: -3.193
• logistic score cutoff: -2.875. If the score is > -2.875, then the woman is at risk for preterm delivery.
• The number of risk factors present is associated with increased risk of preterm delivery, with the risk increasing as the number of risk factors increase.
Individual risk factors:
(1) 4 of the factors are not associated with high risk by themselves: history of previous induced abortion, cigarette use, previous urinary tract infection, and previous neonatal death. The presence of 2 or more of these factors places the person at high risk.
(2) The presence of any one of the remaining 18 factors indicates that the person is at high risk.
Performance:
• 89% of women delivering at <= 28 weeks of gestation were identified
• 79% of women delivering at <= 32 weeks gestation were identified
• only about 56% of women delivering at <= 37 weeks gestation were identified
• Performance better for multipara and multigravid women.
• Specificity improved as the number of risk factors increased, but the sensitivity decreased.
Purpose: To evaluate a pregnant woman for risk of preterm delivery using the risk scoring system of Ross et al.
Specialty: Obstetrics & Gynecology
Objective: risk factors
ICD-10: O60,
