Background
Methods
Study design
Patients and Materials
Reference Method
Test platforms
Test procedures
Statistical Analysis
For P. falciparum | ||
---|---|---|
Test Line(s) visible | Species identification by microscopy corrected by PCR | |
P. falciparum
| P. vivax, P. ovale, P. Malariae /no parasites detected | |
Only HRP-2 or both HRP-2 and pan-pLDH | True positive | Species mismatch*/false positive |
No test line or only pan-pLDH | False negative/species mismatch** | True negative |
For non-
falciparum
species
| ||
Test Line(s) visible | Species identification by microscopy corrected by PCR | |
P. vivax, P. ovale or P. malariae | P. falciparum /no parasites detected | |
Only pan-pLDH | True positive | Species mismatch*/false positive |
No test line or only HRP-2 or both HRP-2 and pan-pLDH | False negative/species mismatch*** | True negative |
Analysis of species mismatch
Ease of use
Ethical review
Results
Sample collection
Species identification by microscopy corrected by PCR | ||||||
---|---|---|---|---|---|---|
Geography | P. falciparum | P. vivax | P. ovale | P. malariae | No parasites seen | |
Africa (n = 444)
| Eastern Africa | 18 | 12 | 9 | 5 | 10 |
Northern Africa | 1 | 1 | 1 | |||
Middle Africa | 97 | 5 | 24 | 7 | 37 | |
Southern Africa | 6 | 1 | 1 | 1 | ||
Western Africa | 145 | 4 | 27 | 6 | 25 | |
Africa | 1 | |||||
Asia (n = 54)
| Eastern Asia | 1 | 3 | |||
Southern Asia | 4 | 16 | 1 | 5 | ||
South-Eastern Asia | 10 | 10 | 1 | |||
Western Asia | 1 | 1 | ||||
Asia | 1 | |||||
Latin America
and the Caribbean (n = 12)
| Caribbean | 1 | 1 | |||
South America | 6 | 1 | 3 | |||
Oceania
(n = 4)
| Melanesia | 1 | 2 | |||
Micronesia | 1 | |||||
No data (n = 76)
| 36 | 18 | 12 | 4 | 6 | |
Total (n = 590)
| 320 | 76 | 76 | 23 | 95 |
Results corrected by PCR | ||||||
---|---|---|---|---|---|---|
Results of microscopy
| Negative |
P. falciparum
|
P. vivax
|
P. ovale
|
P. malariae
|
Total
|
Negative | 95 | 95 | ||||
P. falciparum
| 320 | 320 | ||||
P. vivax
| 72 | 7 | 79 | |||
P. ovale
| 4 | 69 | 73 | |||
P. malariae
| 23 | 23 | ||||
Total
| 95 | 320 | 76 | 76 | 23 | 590 |
Test characteristics
HRP-2 line positive | HRP-2 line negative | |||
---|---|---|---|---|
Samples | pan-pLDH line positive | pan-pLDH line negative | pan-pLDH line positive | pan-pLDH line negative |
P. falciparum (n = 320) | 244 | 40 | 8* | 28 |
P. vivax (n = 76) | 2* | - | 59 | 15 |
P. ovale (n = 76) | - | 1* | 14 | 61 |
P. malariae (n = 23) | - | - | 7 | 16 |
Negative (n = 95) | - | - | - | 95 |
Results of microscopy corrected by PCR | Numbers | Identified as P. falciparum by CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test | % Sensitivity (95% C.I.) | % Specificity (95% C.I.) |
---|---|---|---|---|
All
P. falciparum
samples
| 320 | 284 | 88.8 (84.8-92.0) | |
Pure gametocytaemia | 17 | 12 | 70.6 (44.0-89.7) | |
Asexual parasite density 0-100/μl | 56 | 39 | 69.6 (55.9-81.2) | |
Asexual parasite density 101-200/μl | 35 | 29 | 82.9 (66.4-93.4) | |
Asexual parasite density 201-1,000/μl | 79 | 72 | 91.1 (82.6-96.4) | |
Asexual parasite density > 1,000/μl | 133 | 132 | 99.3 (95.9-100) | |
Asexual parasite density > 100/μl | 247 | 233 | 94.3 (90.7-96.9) | |
All other species and no parasites seen
| 270 | 3 | 98.9 (96.8-99.8) | |
No parasites seen | 95 | 0 | 100.0 (96.2-100) | |
P. vivax
| 76 | 2 | ||
P. ovale
| 76 | 1 | ||
P. malariae
| 23 | 0 |
Results of microscopy corrected by PCR | Numbers | Identified as non-falciparum species by CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test | % Sensitivity (95% C.I.) | % Specificity (95% C.I.) |
---|---|---|---|---|
All non-
falciparum
species combined
| 175 | 80 | 45.7 (38.2-53.4) | |
P. vivax
samples, total
| 76 | 59 | 77.6 (66.6-86.4) | |
Parasite density ≤ 500/μl | 25 | 13 | 52.0 (31.3-72.2) | |
Parasite density > 500/μl | 51 | 46 | 90.2 (78.6-96.7) | |
P. ovale
samples, total
| 76 | 14 | 18.4 (10.5-29.0) | |
Parasite density ≤ 500/μl | 35 | 1 | 2.9 (0.1-14.9) | |
Parasite density > 500/μl | 41 | 13 | 31.7 (18.1-48.1) | |
P. malariae
samples, total
| 23 | 7 | 30.4 (13.2-52.9) | |
Parasite density ≤ 500/μl | 11 | 1 | 9.1 (0.2-41.3) | |
Parasite density > 500/μl | 12 | 6 | 50.0 (21.1-78.9) | |
P. falciparum
and negative samples, total
| 415 | 8 | 98.1 (96.2-99.2) | |
P. falciparum
| 320 | 8 | 97.5 (95.1-98.9) | |
No parasites seen | 95 | 0 | 100.0 (96.2-100) |
Line intensity reading
Line intensity readings, number of samples | ||||||
---|---|---|---|---|---|---|
Results of microscopy corrected by PCR | Negative | Faint | Weak | Medium | Strong | Total |
All
P. falciparum
samples
| 36 | 13 | 66 | 66 | 139 | 320 |
Pure gametocytaemia | 5 | 3 | 3 | 2 | 4 | 17 |
Asexual parasite density 0-100/μl | 17 | 5 | 19 | 8 | 7 | 56 |
Asexual parasite density 101-200/μl | 6 | 2 | 11 | 9 | 7 | 35 |
Asexual parasite density 201-1,000/μl | 7 | 3 | 13 | 18 | 38 | 79 |
Asexual parasite density > 1,000/μl | 1 | 20 | 29 | 83 | 133 | |
Asexual parasite density > 100/μl | 14 | 5 | 44 | 56 | 128 | 247 |
All other species and no parasites seen
| 267 | 2 | 1 | 270 | ||
No parasites seen | 95 | 95 | ||||
P. vivax
| 74 | 1 | 1 | 76 | ||
P. ovale
| 75 | 1 | 76 | |||
P. malariae
| 23 | 23 |
Line intensity readings, number of samples | ||||||
---|---|---|---|---|---|---|
Results of microscopy corrected by PCR | Negative | Faint | Weak | Medium | Strong | Total |
All
P. falciparum
samples
| 69 | 60 | 62 | 12 | 117 | 320 |
Pure gametocytaemia | 8 | 2 | 4 | 3 | 17 | |
Asexual parasite density 0-100/μl | 36 | 17 | 3 | 56 | ||
Asexual parasite density 101-200/μl | 13 | 11 | 10 | 1 | 35 | |
Asexual parasite density 201-1,000/μl | 11 | 30 | 34 | 3 | 1 | 79 |
Asexual parasite density > 1,000/μl | 1 | 0 | 11 | 8 | 113 | 133 |
Asexual parasite density > 100/μl | 25 | 41 | 55 | 12 | 114 | 247 |
All other species and no parasites seen
| 188 | 20 | 29 | 14 | 19 | 270 |
No parasites seen | 95 | 95 | ||||
P. vivax
| 15 | 7 | 24 | 11 | 19 | 76 |
P. ovale
| 62 | 11 | 3 | 76 | ||
P. malariae
| 16 | 2 | 2 | 3 | 23 |
Inter-observer agreement and reproducibility
Overall agreement between three observers (%) | Agreement between pairs of observers (kappa values) | |
---|---|---|
Results expressed as positive and negative readings | ||
HRP-2 | 98.0 | 0.98, 0.97, 0.97 |
pan-pLDH | 90.3 | 0.87, 0.87, 0.87 |
Results expressed as line intensity readings | ||
HRP-2 | 80.7 | 0.82, 0.80, 0.79 |
pan-pLDH | 75.3 | 0.77, 0.77, 0.77 |
Readings HRP-2 line Observer | |||
---|---|---|---|
Species and parasite density |
Observer 1
|
Observer 2
|
Observer 3
|
P. falciparum
| |||
85 asexual parasites/μl | S S S S S | S S S S S | S S S S S |
90 asexual parasites/μl | M M M M M | M W M M W | M M M M M |
180 asexual parasites/μl | N N F N N | N N F N N | N N N N N |
200 asexual parasites/μl | M M M M M | W M W M W | W M M M M |
244 asexual parasites/μl | M M M M M | M M M W M | M M M M M |
465 asexual parasites/μl | M M S M M | M M S M M | M S S S S |
720 asexual parasites/μl | S M S S S | M M M S S | S M S S S |
4,464 asexual parasites/μl | M M M M M | M M M M M | S M M S S |
1,000,000 asexual parasites/μl | W W W M W | W W W W F | W W W W W |
P. malariae
| |||
275 asexual parasites/μl | N F N N N | N F N N N | N F N N N |
1,215 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
P. ovale
| |||
468 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
1,100 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
P. vivax
| |||
432 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
846 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
Readings pan-pLDH line Observer | |||
---|---|---|---|
Sample and parasite density |
Observer 1
|
Observer 2
|
Observer 3
|
P. falciparum
| |||
85 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
90 asexual parasites/μl | F F F F F | F F F F F | N F F F F |
180 asexual parasites/μl | F F F F F | F F F F F | F F F F F |
200 asexual parasites/μl | W W W W W | W W F W F | F W W F F |
244 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
465 asexual parasites/μl | F F W W F | F F F F F | F F F F W |
720 asexual parasites/μl | W W W W W | W F W W F | W W W W F |
4,464 asexual parasites/μl | W W W W W | W W F W W | W W F W W |
1,000,000 asexual parasites/μl | S S S S S | S S S S S | S S S S S |
P. malariae
| |||
275 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
1,215 asexual parasites/μl | W W W W W | F W F F F | N W F F W |
P. ovale
| |||
468 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
1,100 asexual parasites/μl | N N N N N | N N N N N | N N N N N |
P. vivax
| |||
432 asexual parasites/μl | W W W W W | W W W W W | W W W W W |
846 asexual parasites/μl | M M M M M | M S W W W | M M W W M |
Effect of parasite density and duration of storage on test sensitivity
Odds Ratio | P | 95% CI | |
---|---|---|---|
P. falciparum
(n = 320)
| |||
Number of years of storage | 0.97 | 0.675 | 0.86-1.10 |
Log10 parasite densities | 2.04 | 0.000 | 1.50-2.76 |
P. vivax
(n = 76)
| |||
Number of years of storage | 0.94 | 0.451 | 0.79-1.11 |
Log10 parasite densities | 3.56 | 0.003 | 1.55-8.18 |
P. ovale
(n = 76)
| |||
Number of years of storage | 0.73 | 0.003 | 0.60-0.90 |
Log10 parasite densities | 12.19 | 0.005 | 2.12-70.23 |
P. malariae
(n = 23)
| |||
Number of years of storage | 0.80 | 0.185 | 0.57-1.12 |
Log10 parasite densities | 33.10 | 0.029 | 1.43-768.88 |