Variability in white blood cell count during uncomplicated malaria and implications for parasite density estimation: a WorldWide Antimalarial Resistance Network individual patient data meta-analysis

Table 1 Patient characteristics at enrolment into studies, by species

Parameter	N	Plasmodium falciparum	N	Plasmodium vivax
Parameter	N	Median [min; max] or n [%]	N	Median [min; max] or n [%]
Age (years)	24978	4.9 [0.1; 86.7]	2678	24.6 [0.3; 79.0]
Age group	24978		2678
< 1 year		1044 [4.2]		2 [0.1]
1–4 years		11606 [46.5]		168 [6.3]
5–14 years		5797 [23.2]		501 [18.7]
15 + years		6531 [26.1]		2007 [74.9]
Male sex	24978	14061 [56.3]	2678	1875 [70.0]
Underweight¹	12549	2280 [18.2]	170	49 [28.8]
WAZ score¹	12549	− 1.0 [− 5.8; 4.9]	170	− 1.2 [− 4.6; 2.0]
Wasted²	7943	792 [10.0]	34	5 [14.7]
WHZ score²	7943	− 0.32 [− 4.9; 5.0]	34	− 0.8 [− 4.2;2.0]
Temperature (°C)	22875	38.0 [34.0; 42.0]	2060	37.4 [34.5; 42.0]
Fever present³	23684	15981 [67.5]	2076	1032 [49.7]
Haemoglobin (g/dL)	18687	10.0 [3.1; 26.0]	2596	12.3 [3.9; 18.9]
Haematocrit (%)	13721	34.0 [8.6; 63.0]	1404	39.2 [19.0; 52.3]
Anaemia⁴	24272		2605
No anaemia		13695 [56.4]		2292 [88.0]
Moderate anaemia		9196[37.9]		294 [11.3]
Severe anaemia		1381 [5.7]		19 [0.7]
Parasitaemia (/µL)	24978	17072 [7; 1528753]	2678	3002 [16; 77035]
Hyperparasitaemia⁵	24978	3124 [12.5]	N/A	N/A
Transmission intensity [P. falciparum only]⁶	24978
Low		15544 [62.2]
Moderate		3588 [14.4]
High		5846 [23.4]
Relapse periodicity [P.vivax only]⁷			2678
Long periodicity				1179 [44.0]
Short periodicity				1499 [56.0]
Region	24978		2678
Africa		16747 [67.0]		0 [0]
Asia–Pacific		8102 [32.4]		2079 [77.6]
Americas		129 [0.5]		599 [22.4]

¹ Evaluated only in children < 5 years of age. WAZ = weight of age z-score. Underweight defined as a WAZ < − 2
² Evaluated only in children < 5 years of age. WHZ = weight for height z-score. Wasted defined as WHZ < − 2
³ Defined as a day 0 temperature of ≥ 37.5 °C
⁴ Severe anaemia = Hb < 7 g/dL; moderate anaemia = Hb 7 to < 10 g/dL
⁵ P. falciparum hyperparasitaemia defined as a parasite count ≥ 100,000/µL as reported in the study
⁶ P. falciparum transmission intensity defined according to age-standardised parasite rate, where: Low = 0 to 15%, Medium 15 to 40%, High ≥ 40%
⁷P. vivax relapse periodicity defined as: Low ≤ 47 days, High > 47 days
N number evaluated. n number with the characteristic. N/A not applicable. WBC white blood cell

ISSN: 1475-2875