Table 1
Mean and standard deviation of creatinine values from the point-of-care devices and laboratory analysis used in the Nicaraguan and Guatemalan studies. Average differences and 95% confidence intervals between laboratory values and unadjusted point-of-care devices.
| STATSENSOR (GT) N = 109 | STATSENSOR (GT) N = 192 | STATSENSOR (Nic) N = 158 | I-STAT (NIC) N = 213 | |||||
|---|---|---|---|---|---|---|---|---|
| POPULATION | SUGARCANE CUTTERS, PRE-WORK SHIFT | SUGARCANE CUTTERS, POST-WORK SHIFT1 | COMMUNITY POPULATION, CASE-CONTROL STUDY FOLLOW-UP | COMMUNITY POPULATION, HIGH-RISK FAMILIES2 | ||||
| MEAN (SD OR 95% CI) | P-VALUE | MEAN (SD OR 95% CI) | P-VALUE | MEAN (SD OR 95% CI) | P-VALUE | MEAN (SD OR 95% CI) | P-VALUE | |
| Lab creatinine measure | 0.87 (0.19) | 0.88 (0.21) | 1.10 (1.04) | 1.89 (1.98) | ||||
| Unadjusted POC creatinine measure | 0.85 (0.22) | 1.08 (0.35) | 1.58 (1.60) | 1.96 (2.20) | ||||
| Difference (Serum lab – POC unadjusted) | 0.02 (–0.01, 0.05) | 0.14 | –0.20 (–0.24, –0.17) | <0.001 | –0.48 (–0.58, –0.38) | <0.001 | –0.07 (–0.12, –0.02) | 0.01 |
[i] 1 Griffin, B.R., et al., Unadjusted point of care creatinine results overestimate acute kidney injury incidence during field testing in Guatemala. PloS one, 2018. 13(9): p. e0204614–e0204614.
2 Kupferman, J., et al., Characterization of Mesoamerican Nephropathy in a Kidney Failure Hotspot in Nicaragua. American Journal of Kidney Diseases, 2016. 68(5): p. 716–725.
Figure 1
Top: Correlation and agreement between i-STAT point-of-care creatinine values and CNDR laboratory creatinine values from the 2015–2016 Nicaragua study. Bottom: Bland-Altman plot of agreement between i-STAT point-of-care creatinine values and CNDR laboratory creatinine values.
Figure 2
Top: Correlation and agreement between StatSensor Creatinine point-of-care creatinine values and CNDR laboratory creatinine values from the 2015 Nicaragua study. Bottom: Bland-Altman plot of agreement between StatSensor Creatinine point-of-care creatinine values and CNDR laboratory creatinine values.
Figure 3
Top: Correlation and agreement between StatSensor Creatinine point-of-care creatinine values and HLL laboratory creatinine values from the pre-shift November 2017 Guatemala data. Bottom: Bland-Altman plot of agreement between StatSensor Creatinine point-of-care creatinine values and HLL laboratory cretainine values.
Table 2
Correction factor for each of the studies based on linear regression with no intercept. Calculated adjusted point-of-care creatinine measurements based on the study-specific correction factor as well as application of the Griffin et al., 2018 correction factor. Mean and 95% confidence intervals for differences between adjusted point-of-care creatinine and laboratory creatinine values.
| LAB VALUE | POC VALUE | CORRECTION FACTOR LINEAR REGRESSION | CORRECTION FACTORGRIFFIN ET AL., 2018 | ADJUSTED POCLINEAR REGRESSION | ADJUSTED POCGRIFFIN ET AL., 2018 | DIFFERENCE LAB ANDADJUSTED POCLINEAR REGRESSION | DIFFERENCE LAB ANDADJUSTED POC GRIFFIN ET AL., 2018 | |
|---|---|---|---|---|---|---|---|---|
| StatSensor Creatinine November 2017 GuatemalaN = 109 | 0.87 (0.19) | 0.85 (0.22) | 1.00 | 0.78 | 0.85 (0.22) | 0.66 (0.17) | 0.02 (–0.01, 0.05) | 0.21 (0.18, 0.23) |
| StatSensor Creatinine 2015 NicaraguaN = 158 | 1.10 (1.04) | 1.58 (1.60) | 0.66 | 1.04 (1.06) | 1.23 (1.25) | 0.06 (0.02, 0.09) | –0.14 (–0.19, –0.08) | |
| StatSensor Creatinine 2015 Nicaragua – Subset1N = 137 | 0.77 (0.35) | 1.06 (0.40) | 0.73 | 0.78 (0.29) | 0.83 (0.31) | –0.01 (–0.04, 0.02) | –0.06 (–0.09, –0.03) | |
| i-STAT 2015-2016 NicaraguaN = 213 | 1.89 (1.98) | 1.96 (2.20) | 0.92 | 1.80 (2.02) | 0.09 (0.05, 0.13) |
[i] a Assessing a creatinine cutoff of 1.5 mg/dL.
Table 3
Summary of WHO ASSURED criteria as applied to the i-STAT, StatSensor Creatinine, and laboratory measurements of creatinine. Pooled StatSensor Creatinine data was used to calculate sensitivity and specificity, with laboratory measurements as the gold standard.
| CHARACTERISTIC | I-STAT | STATSENSOR CREATININE | LABORATORY |
|---|---|---|---|
| Affordable | $14,000 per device$20 per test for Cr and other serum measures | $3,600 per device$6 per Cr test | Local costs vary |
| Sensitivea | 99% | 100% | Gold standard with adequate laboratory infrastructure |
| Specifica | 86% | 92% | Gold standard with adequate laboratory infrastructure |
| User-friendly | ✔ | ✔ | Lab technician required |
| Rapid | 2 minutes | 30 seconds | Days to weeks |
| Equipment-free | Cooler in hot climate | Cooler in hot climate | Electricity and refrigeration |
| Deliverable | ✔ | ✔ | ✖ |
[i] 1 Creatinine measures > 2.59 mg/dL (n = 21) were removed in the subset.
Table 4
Sensitivity, specificity, and positive predictive value of creatinine levels detected at a threshold of 1.5 mg/dL for StatSensor and i-STAT compared to laboratory measurement.
StatSensor Creatinine—Sensitivity: 97%; Specificity: 95%; Positive predictive value: 71%.
i-STAT—Sensitivity: 99%; Specificity: 92%; Positive predictive value: 90%.
| ≥1.5 MD/DL | LAB IDENTIFIED | ||
|---|---|---|---|
| < 1.5 MG/DL | |||
| StatSensor Creatinine Identified | ≥1.5 md/dL | 29 | 12 |
| <1.5 mg/dL | 1 | 225 | |
| i-STAT Identified | ≥1.5 md/dL | 86 | 10 |
| <1.5 mg/dL | 1 | 116 | |
Table 5
Distribution of measured creatinine values in each of the study populations.
| N | MEASURED CREATININE (MG/DL) | ||||
|---|---|---|---|---|---|
| <1.3 | 1.3–1.49 | 1.5–1.7 | >1.7 | ||
| i-STAT (Nicaragua) | 213 | 104 (48.8%) | 13 (6.1%) | 23 (10.8%) | 73 (34.3%) |
| StatSensor Creatinine (Combined) | 267 | 217 (81.3%) | 9 (3.4%) | 8 (3.0%) | 33 (12.4%) |
| StatSensor Creatinine (Nicaragua) | 158 | 113 (71.5%) | 6 (3.8%) | 7 (4.4%) | 32 (20.3%) |
| StatSensor Creatinine (Guatemala) | 109 | 104 (95.4%) | 3 (2.8%) | 1 (0.9%) | 1 (0.9%) |