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Table 6 Performance of predictive generalised linear models in South Sudan, by acute malnutrition outcome

From: Can we predict the burden of acute malnutrition in crisis-affected countries? Findings from Somalia and South Sudan

Statistic

Categorical outcomes

Continuous outcomes

SAM (WFH + oedema)

GAM (WFH + oedema)

SAM (MUAC + oedema)

GAM (MUAC + oedema)

WFH

MUAC

Predictors: coefficient† on training data

Incidence of acute flaccid paralysis

previous 3mths

 

previous 3mths

previous 3mths

 

previous 3mths

 0 per 100,000

[ref.]

 

[ref.]

[ref.]

 

[ref.]

 0.01 to 0.49 per 100,000

0.94

 

0.80*

0.99

 

0.08**

 ≥ 0.50 per 100,000

1.17*

 

1.19

1.16**

 

-0.03

Main local livelihood type

 Agriculturalists

 

[ref.]

  

[ref.]

[ref.]

 Agro-pastoralists

 

1.46***

  

-0.30***

-0.21***

 Displaced

 

1.44***

  

-0.36***

-0.09*

 Pastoralists

 

1.02

  

-0.15***

-0.13**

Total rainfall

previous 6mths

previous 6mths

  

previous 6mths

 

 < 50mm

[ref.]

[ref.]

  

[ref.]

 

 50 to 99mm

0.98

0.99

  

-0.02

 

 100 to 149mm

0.74***

0.80***

  

0.11***

 

 ≥ 150mm

0.78

0.97

  

0.00

 

Terms of trade (flour-goat exchange)

3-5mths prior

4-6mths prior

  

4-6mths prior

 

 < 20.0Kg

[ref.]

[ref.]

  

[ref.]

 

 20.0 to 29.9Kg

0.88*

0.80***

  

0.15***

 

 30.0 to 39.9Kg

0.70***

0.84***

  

0.10***

 

 ≥ 40.0 Kg

0.81**

1.00

  

0.02

 

Incidence of measles

 

2-4mths prior

 

1-3mths prior

1-3mths prior

1-3mths prior

 0

 

[ref.]

 

[ref.]

[ref.]

[ref.]

 > 0

 

1.06

 

1.16*

-0.04

-0.07*

Doses of measles vaccine administered

  

3-5mths prior

   

 0 per 100,000

  

[ref.]

   

 0.1 to 99.9 per 100,000

  

1.24

   

 100.0 to 199.9 per 100,000

  

1.21

   

 200.0 to 299.9 per 100,000

  

1.74***

   

 ≥ 300.0 per 100,000

  

1.14

   

Estimation performance

Mean square error

training data

0.00046

0.00297

0.00017

0.00198

0.05358

0.10680

LOOCV

0.00056

0.00368

0.00020

0.00221

0.06670

0.12667

holdout data

0.00039

0.00342

0.00009

0.00150

0.06680

0.09943

Relative bias

LOOCV

+41.1%

+12.7%

+80.9%

+38.9%

+9.9%

0.0%

holdout data

+49.1%

+14.4%

+88.4%

+20.5%

+16.0%

-0.1%

Relative precision of 95%CI

LOOCV

±11.4%

±5.4%

±16.4%

±4.8%

±2.9%

±0.2%

holdout data

±11.4%

±6.1%

±16.1%

±4.6%

±3.3%

±0.2%

Coverage of 95%CI

LOOCV

64.3%

45.1%

68.7%

49.6%

38.9%

30.4%

holdout data

66.1%

58.9%

82.1%

57.1%

30.4%

48.2%

Coverage of 80%CI

LOOCV

44.3%

29.2%

47.0%

34.8%

28.3%

26.1%

holdout data

46.4%

33.9%

60.7%

42.9%

21.4%

33.9%

Classification performance by SAM/GAM prevalence threshold (n = denominator of percentage)

Sensitivity, lower threshold

LOOCV

≥2%

100.0% (97)

≥15%

89.7%

(78)

≥2%

28.1%

(32)

≥15%

0.0%

(9)

n/a

holdout data

100.0%

(48)

93.8%

(32)

27.3%

(11)

0.0%

(4)

Sensitivity, upper threshold

LOOCV

≥5%

31.0%

(42)

≥20%

60.0%

(45)

≥5%

0.0%

(3)

≥20%

0.0%

(2)

holdout data

42.9%

(14)

35.3%

(17)

n/a

(0)

0.0%

(2)

Specificity, lower threshold

LOOCV

<2%

0.0%

(18)

<15%

40.0%

(35)

<2%

86.7%

(83)

<15%

100.0%

(106)

holdout data

0.0%

(8)

25.0%

(24)

100.0%

(45)

100.0%

(52)

Specificity, upper threshold

LOOCV

<5%

76.7%

(73)

<20%

76.5%

(68)

<5%

100.0%

(112)

<20%

100.0%

(113)

holdout data

90.5%

(42)

87.2%

(39)

100.0%

(56)

100.0%

(54)

  1. †Odds ratio for categorical outcomes; linear coefficient for continuous outcomes
  2. *0.01 ≤ p-value < 0.05 ** 0.001 ≤ p-value < 0.01 *** p-value < 0.001
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BMC Nutrition

ISSN: 2055-0928

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