1. Introduction
1.1. Background
1.1.1. Data collection in emergency settings
1.1.2 Background on LQAS
1.1.3. LQAS hypothesis test of GAM prevalence with the 33 × 6 and 67 × 3 designs
1.1.4. Field validation sites
2. Analysis
2.1. Methods
2.1.1. Data collection
2.1.2. Data cleaning
2.1.3. Data analysis
Sampling design
| |||
---|---|---|---|
Data collection component
|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
|
Drive to 1st cluster of day | 7.9 | 8.5 | 11.3 |
Locate 1st household in cluster | 14.2 | 12.2 | 14.6 |
Walk household to household in cluster | 3.0 | 3.0 | 3.0 |
Administer questionnaire (0 children in household) | 7.1 | 7.1 | 7.1 |
Administer questionnaire (children in household) | 15.1 | 15.1 | 15.1 |
Drive to next cluster of same design | 5.8 | 6.7 | 27.8 |
Drive back to base at end of day | 6.2 | 11.4 | 12.8 |
Sampling design
| |||
---|---|---|---|
Data collection component
|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
|
Drive to 1st cluster of day | 29.6 | 25.8 | 21.7 |
Locate 1st household in cluster | 8.3 | 9.8 | 15.5 |
Walk household to household in cluster | 2.0 | 2.0 | 2.0 |
Administer questionnaire (0 children in household) | 4.8 | 4.8 | 4.8 |
Administer questionnaire (children in household) | 10.5 | 10.5 | 10.5 |
Drive to next cluster of same design | 2.3 | 2.0 | 5.2 |
Drive back to base at end of day | 15.4 | 28.6 | 20.8 |
2.2. Results
2.2.1. Estimation and precision of child-level indicators
Indicator
|
Sampling design
| ||
---|---|---|---|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
| |
GAM | 8.1 (3.6, 12.5) +/- 4.5 | 6.5 (3.0, 9.9) +/- 3.5 | 8.6 (6.5, 10.8) +/- 2.2 |
Low MUAC (<12.5 cm) | 5.6 (1.7, 9.4) +/- 3.9 | 4.5 (1.7, 7.3) +/- 2.8 | 3.8 (2.1, 5.5) +/- 1.7 |
Stunting | 33.8 (25.0, 42.6) +/- 8.8 | 36.6 (29.6, 43.6) +/- 7.0 | 32.3 (29.9, 34.7) +/- 2.4 |
Underweight | 34.3 (26.7, 42.0) +/- 7.7 | 34.1 (27.9, 40.3) +/- 6.2 | 31.6 (27.9, 35.2) +/- 3.7 |
BCG vaccination | 33.8 (24.6, 43.1) +/- 9.3 | 34.3 (26.1, 42.6) +/- 8.3 | 45.6 (38.7, 52.5) +/- 6.9 |
Measles vaccination | 41.5 (30.5, 52.4) +/- 11.0 | 52.2 (42.6, 61.8) +/- 9.6 | 56.9 (47.0, 66.8) +/- 9.9 |
VAC supplementation (5.5 month recall) | 78.4 (68.5, 88.2) +/- 9.9 | 81.3 (73.4, 89.3) +/- 8.0 | 83.5 (72.9, 94.1) +/- 10.6 |
Diarrhea (2 week recall) | 11.6 (7.0, 16.2) +/- 4.6 | 14.9 (9.4, 20.5) +/- 5.6 | 9.3 (5.9, 12.6) +/- 3.4 |
ARI (2 week recall) | 10.1 (3.7, 16.5) +/- 6.4 | 16.7 (11.4, 21.9) +/- 5.3 | 5.9 (2.7, 9.1) +/- 3.2 |
Fever (2 week recall) | 21.2 (14.1, 28.4) +/- 7.2 | 17.9 (11.7, 24.1) +/- 6.2 | 14.6 (11.2, 18.0) +/- 3.4 |
Indicator
|
Sampling design
| ||
---|---|---|---|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
| |
GAM | 4.7 (1.9, 7.4) +/- 2.8 | 8.0 (4.5, 11.5) +/- 3.5 | 6.9 (4.8, 9.0) +/- 2.1 |
Low MUAC (<12.5 cm) | 4.0 (0.7, 7.4) +/- 3.4 | 3.0 (0.7, 5.3) +/- 2.3 | 3.3 (2.0, 4.7) +/- 1.4 |
Stunting | 26.0 (19.1, 32.8) +/- 6.9 | 25.4 (19.4, 31.4) +/- 6.0 | 27.3 (23.8, 30.9) +/- 3.6 |
Underweight | 22.9 (16.8, 29.1) +/- 6.2 | 27.6 (21.1, 34.1) +/- 6.5 | 27.4 (24.0, 30.9) +/- 3.5 |
BCG vaccination | 26.8 (16.4, 37.1) +/- 10.4 | 40.3 (31.6, 49.0) +/- 8.7 | 35.2 (28.0, 42.5) +/- 7.3 |
Measles vaccination | 57.4 (43.7, 71.1) +/- 13.7 | 55.0 (45.0, 65.0) +/- 10.0 | 55.4 (45.3, 65.5) +/- 10.1 |
VAC supplementation (5.5 month recall) | 74.1 (61.7, 86.6) +/- 12.5 | 69.7 (59.7, 79.6) +/- 10.0 | 77.7 (67.1, 88.4) +/- 10.7 |
Diarrhea (2 week recall) | 6.6 (2.2, 11.0) +/- 4.4 | 6.0 (2.3, 9.7) +/- 3.7 | 10.9 (6.6, 15.2) +/- 4.3 |
ARI (2 week recall) | 6.1 (1.9, 10.2) +/- 4.2 | 6.0 (2.0, 10.0) +/- 4.0 | 3.4 (1.9, 5.0) +/- 1.6 |
Fever (2 week recall) | 16.2 (9.8, 22.5) +/- 6.4 | 21.6 (15.3, 28.0) +/- 6.4 | 18.4 (14.5, 22.2) +/- 3.9 |
2.2.2. LQAS hypothesis test of GAM prevalence
Sampling design
|
n
|
Decision rule (# of children with acute malnutrition) to reject H
o
| ||
---|---|---|---|---|
10% GAM threshold
|
15% GAM threshold
|
20% GAM threshold
| ||
33 × 6 design | 198 | ≤ 13 (α = 0.06, β = 0.12) | ≤ 23 (α = 0.10, β = 0.18) | ≤ 33 (α = 0.13, β = 0.22) |
67 × 3 design | 201 | ≤ 13 (α = 0.05, β = 0.13) | ≤ 23 (α = 0.09, β = 0.20) | ≤ 33 (α = 0.11, β = 0.24) |
Sampling design
|
# of children with acute malnutrition in sample
|
n (actual sample size)
|
Decision rule (# of children with acute malnutrition) to reject H
o
| ||
---|---|---|---|---|---|
10% GAM threshold
|
15% GAM threshold
|
20% GAM threshold
| |||
33 × 6 design | 16 | 192 | ≤ 13 (α = 0.07, β = 0.10) | ≤ 22* (α = 0.09, β = 0.21) | ≤ 32* (α = 0.14, β = 0.22) |
67 × 3 design | 12 | 194 | ≤ 13 (α = 0.07, β = 0.10) | ≤ 22* (α = 0.08, β = 0.22) | ≤ 32* (α = 0.13, β = 0.24) |
Sampling design
|
# of children with acute malnutrition in sample
|
n (actual sample size)
|
Decision rule (# of children with acute malnutrition) to reject H
o
| ||
---|---|---|---|---|---|
10% GAM threshold
|
15% GAM threshold
|
20% GAM threshold
| |||
33 × 6 design | 9 | 197 | ≤ 13 (α = 0.06, β = 0.11) | ≤ 23 (α = 0.11, β = 0.18) | ≤ 33 (α = 0.14, β = 0.21) |
67 × 3 design | 16 | 199 | ≤ 13 (α = 0.05, β = 0.12) | ≤ 23 (α = 0.10, β = 0.19) | ≤ 33 (α = 0.13, β = 0.23) |
2.2.3. Estimation and precision of household-level indicators
Indicator
|
Sampling design
| ||
---|---|---|---|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
| |
Access to potable water | 61.1 (46.2, 76.0) +/- 14.9 | 48.3 (36.8, 59.7) +/- 11.5 | 49.8 (34.0, 65.6) +/- 15.8 |
Access to latrine | 50.0 (36.9, 63.1) +/- 13.1 | 46.8 (37.6, 56.0) +/- 9.2 | 44.6 (33.7, 55.4) +/- 10.9 |
Ownership of bed net | 55.8 (45.1, 66.4) +/- 10.7 | 53.5 (45.2, 61.7) +/- 8.3 | 47.8 (42.6, 53.1) +/- 5.3 |
Food shortage (5.5 month recall) | 75.3 (64.7, 85.8) +/- 10.6 | 51.5 (42.3, 60.7) +/- 9.2 | 47.8 (38.1, 57.4) +/- 9.7 |
Indicator
|
Sampling design
| ||
---|---|---|---|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
| |
Access to potable water | 52.0 (34.6, 69.4) +/- 17.4 | 53.2 (41.2, 65.3) +/- 12.1 | 57.4 (39.7, 75.2) +/- 17.8 |
Access to latrine | 50.5 (37.4, 63.6) +/- 13.1 | 50.3 (40.4, 60.1) +/- 9.9 | 50.8 (39.3, 62.3) +/- 11.5 |
Ownership of bed net | 29.3 (17.1, 41.5) +/- 12.2 | 36.6 (26.5, 46.7) +/- 10.1 | 35.1 (23.7, 46.5) +/- 11.4 |
Food shortage (5.5 month recall) | 66.7 (53.7, 79.6) +/- 13.0 | 62.4 (52.4, 72.5) +/- 10.1 | 61.7 (48.8, 74.6) +/- 12.9 |
2.2.4 Estimation and precision of mortality rates
Indicator
|
Sampling design
| ||
---|---|---|---|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
| |
Crude mortality rate* | 0.67 (0.00†, 1.93) n = 179,498 PDAR | 0.10 (0.00†, 1.28) n = 193,602 PDAR | 0.53 (0.34, 0.72) n = 659,362 PDAR |
Under 5 mortality rate* | 1.17 (0.00†, 4.50) n = 42,804 PDAR | 0.23 (0.00†, 2.50) n = 43,952 PDAR | 0.86 (0.32, 1.40) n = 174,988 PDAR |
Indicator
|
Sampling design
| ||
---|---|---|---|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
| |
Crude mortality rate* | 0.23 (0.00†, 0.85) n = 132,048 PDAR | 0.31 (0.00†, 1.83) n = 160,020 PDAR | 0.18 (0.05, 0.31) n = 626,640 PDAR |
Under 5 mortality rate* | 0.27 (0.00†, 1.55) n = 37,128 PDAR | 0.49 (0.00†, 4.25) n = 41,160 PDAR | 0.36 (0.05, 0.66) n = 169,260 PDAR |
2.2.5. Time expenditure and cost comparisons
Sampling design
|
GAM point estimate (95% CI)
|
GAM LQAS result
|
Team days required to collect data
|
Cost for data collection
|
---|---|---|---|---|
33 × 6 design | 8.1 (3.6, 12.5) | Fail to reject Ho at 10% GAM threshold. Conclude area requires intervention appropriate for 10% threshold level | 8.25 | $1232 |
67 × 3 design | 6.5 (3.0, 9.9) | Reject Ho at 10% GAM threshold. Conclude area has <10% GAM prevalence | 11.17 | $1630 |
30 × 30 design | 8.6 (6.5, 10.8) | NA | 30.00 | $4606 |
Sampling design
|
GAM point estimate (95% CI)
|
GAM LQAS result
|
Team days required to collect data
|
Cost for data collection
|
---|---|---|---|---|
33 × 6 Design | 4.7 (1.9, 7.4) | Reject Ho at 10% GAM threshold. Conclude area has <10% GAM prevalence | 4.13 | NA |
67 × 3 Design | 8.0 (4.5, 11.5) | Fail to reject Ho at 10% GAM threshold. Conclude area requires intervention appropriate for 10% threshold level | 5.58 | NA |
30 × 30 Design | 6.9 (4.8, 9.0) | NA | 15.00 | NA |
Administrative unit
|
Distance assumption
|
Sampling design
|
Length of work day assumption
| ||
---|---|---|---|---|---|
33 × 6 design (in team days)
|
67 × 3 design (in team days)
|
30 × 30 design (in team days)
| |||
Fur Baranga | Actual distance | 8.25 | 11.17 | 30.00 | 8.5 hr work day |
Habila | Actual distance | 4.13 | 5.58 | 15.00 | 12.0 hr work day |
Fur Baranga | 3× Actual distance | 11.00 | 16.75 | 30.00 | 9.5 hr work day |
Habila | 3× Actual distance | 8.25 | 13.40 | 30.00 | 9.0 hr work day |
Fur Barnaga | 5× Actual distance | 11.00 | 22.33 | 30.00 | 11.0 hr work day |
Habila | 5× Actual distance | 11.00 | 22.33 | 30.00 | 9.5 hr work day |
3. Discussion
Sampling design
| |||
---|---|---|---|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
| |
Design effect (rho)
|
Design effect (rho)
|
Design effect (rho)
| |
Child-level Indicators
| |||
GAM | 1.2339 (0.0426) | 0.9602 (0.0000) | 1.2626 (0.0082) |
Low MUAC (<12.5 cm) | 1.3169 (0.0567) | 0.9108 (0.0000) | 1.6112 (0.0197) |
Stunting | 1.6427 (0.1202) | 1.0429 (0.0156) | 0.5487 (0.0000) |
Underweight | 1.2382 (0.0414) | 0.8487 (0.0000) | 1.2919 (0.0087) |
BCG vaccination | 1.8279 (0.1564) | 1.4842 (0.2209) | 4.0857 (0.1020) |
Measles vaccination | 2.1131 (0.2611) | 1.7224 (0.3648) | 7.4488 (0.2562) |
VAC supplementation (5.5 month recall) | 2.5254 (0.3087) | 1.9328 (0.5023) | 16.4399 (0.5503) |
Diarrhea (2 week recall) | 0.9708 (0.0000) | 1.1977 (0.0462) | 2.7355 (0.0584) |
ARI (2 week recall) | 2.1629 (0.2214) | 0.9851 (0.0000) | 3.9733 (0.1006) |
Fever (2 week recall) | 1.4590 (0.0850) | 1.3081 (0.1497) | 1.9390 (0.0305) |
Household-level Indicators
| |||
Access to potable water | 4.4337 (0.6643) | 2.6278 (0.8008) | 21.3793 (0.6802) |
Access to latrine | 3.2750 (0.4384) | 1.6980 (0.3406) | 10.2704 (0.3085) |
Ownership of bed net | 2.1713 (0.2231) | 1.3621 (0.1801) | 2.3255 (0.0442) |
Food shortage (5.5 month recall) | 2.8305 (0.3527) | 1.6889 (0.3431) | 7.9581 (0.2316) |
Sampling design
| |||
---|---|---|---|
33 × 6 design
|
67 × 3 design
|
30 × 30 design
| |
Design effect (rho)
|
Design effect (rho)
|
Design effect (rho)
| |
Child-level indicators
| |||
GAM | 0.8000 (0.0000) | 0.8270 (0.0000) | 1.4208 (0.0129) |
Low MUAC (<12.5 cm) | 1.3447 (0.0621) | 0.9479 (0.0000) | 1.2828 (0.0083) |
Stunting | 1.1454 (0.0248) | 0.9506 (0.0000) | 1.3622 (0.0111) |
Underweight | 1.0007 (0.0000) | 1.0523 (0.0232) | 1.2840 (0.0084) |
BCG vaccination | 2.5743 (0.3024) | 1.5682 (0.2763) | 4.9646 (0.1312) |
Measles vaccination | 3.1927 (0.4966) | 1.8578 (0.4771) | 7.9908 (0.2610) |
VAC supplementation (5.5 month recall) | 3.4622 (0.5364) | 2.1763 (0.6419) | 12.9310 (0.4249) |
Diarrhea (2 week recall) | 1.5103 (0.0944) | 1.2213 (0.1107) | 4.1322 (0.1037) |
ARI (2 week recall) | 1.4232 (0.0774) | 1.3977 (0.1985) | 1.5472 (0.0171) |
Fever (2 week recall) | 1.4139 (0.0756) | 1.1678 (0.0517) | 2.1121 (0.0360) |
Household-level indicators
| |||
Access to potable water | 5.7618 (0.9231) | 2.9092 (0.9401) | 27.6205 (0.8881) |
Access to latrine | 3.2540 (0.4344) | 1.9448 (0.4627) | 11.3895 (0.3456) |
Ownership of bed net | 3.4041 (0.4637) | 2.1906 (0.5939) | 12.1655 (0.3731) |
Food shortage (5.5 month recall) | 3.5912 (0.5000) | 2.1570 (0.5772) | 15.0586 (0.4688) |