Discriminant Function Score of Pine et al for Predicting Survival in Patients with Intra-Abdominal Sepsis

 

Parameters used for score:

(1) shock at any time: defined as clinical reduction in peripheral perfusion and 2 or more of the following:

(1a) systolic blood pressure <= 80 mm Hg for 1 hour;

(1b) pulse > 120 beats per minute with sinus rhythm for 1 hour;

(1c) urine output < 80 mL in 4 hours;

(1d) need for vasopressors to maintain blood pressure for 1 hours.(2) alcohol abuse

(3) age

(4) intestinal infarction

 

Additional factors impacting survival:

(5) malnutrition

(6) organ failure after surgery

Parameter	Finding	Points
shock	absent	0
	present	1
alcohol abuse	absent	0
	present	1
age	age <= 65 years	0
	age > 65 years	1
intestinal infarction	absent	0
	present	1

 

discriminant function =

= (2.7 * (points for shock)) + (1.7 * (points for alcohol abuse)) + (1.6 * (points for age)) + (1.4 * (points for intestinal infarction)) – 1.3

 

Interpretation:

• minimum score: -1.3 (no risk conditions present)

• maximum score: 6.1 (all risk conditions present; in reality scores above 4 infrequent)

• The lower the score the greater the survival.

• Using the probability curve in Figure 4 (page 247) the point of 50% survival in a score of 0.75.

• Whether the probability curve is applicable may be debatable based on the bar graph data in Figure 4. But a score < 0.75 seems to show good survival, while a score >= 2.0 has a poor prognosis.

 

Discriminant Function	Probability of Survival
-1.25/-1.3	100%
-1.0	99%
-0.75	97%
-0.50	95%
-0.25	91%
0	85%
0.25	75%
0.5	65%
0.75	50%
1.0	35%
1.25	25%
1.5	15%
1.75	9%
2.0	5%
2.25	3%
2.5	1%
2.75/2.8	0%

from curve shown in Figure 4, page 247

 

To generate the probability curve

 

probability of survival =

= 1 / (1 + EXP((-1) * X))

 

trial and error shows that

 

X =

= (-2.313 * (DF score)) + 1.7346

 

gives a reasonable approximation in the data in the table and the survival curve.

 

Performance:

• In the 106 patients studied, the score identified outcome in 92% of cases.

 

Limitations:

• Newer diagnostic techniques and therapies should have improved the prognosis since when the study was performed in 1983.