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Table 2 Missing value handling

From: Performance of critical care prognostic scoring systems in low and middle-income countries: a systematic review

Study Scoring system/s Missing value handling
Exclusion
 Celik et al. (2014) [63] SAPS II 178 (21.1%) were excluded due to lack of data, and 46 (5.55%) patients were excluded due to archival documentation problems. No information on admission source, attached devices, PaO2/FiO2 and Glasgow Coma Score was available for the excluded group in the computerised medical records. The included group survey did not differ from the excluded group regarding age, gender, admission time and admission day. The prevalence of trauma and intoxication was higher among the excluded group than the included group (trauma 15%, intoxication 30%)
 Chiavone et al. (2005) [65] APACHE II One patient excluded
 Godinjak et al. (2016) [31] APACHE II
SAPS II
15 patients (7.9%) who died in the first 24 hours after admission to the MICU
 Haidri et al. (2011) [74] APACHE II All patients with incomplete records and missing variables including laboratory investigations or who were not followed up due to any reason were excluded
 Hernandez et al. (2014) [78] SAPS 3 159 (6.6%) were excluded for incomplete SAPS 3 data
 Naqvi et al. (2016) [33] APACHE II
SAPS
29 patients (23.6%) with incomplete information of scoring system in case records
 Naved et al. (2011) [34] APACHE II Patients with incomplete records not included (numbers not reported)
 Willairatna et al. (1995) [82] APACHE II
APACHE III
SAPS II
When scores could not be derived due to an incomplete set of physiological data, patients were excluded
Normal value imputation
 Faruq et al. (2013) [37] APACHE II
SAPS II
GCS attributed as normal
 Khwannimit and Geater (2007) [38] APACHE II
SAPS II
GCS attributed as normal
Missing physiological variables were found in only 6% for APACHE II (excluding bilirubin, which was missing in 76.5% of the presented data records) and 6.3% for SAPS II variables (excluding bilirubin, which was missing in 76.5% of the presented data records)
 Soares et al. (2004) [40] APACHE II
APACHE III
MPM II (0)
MPM II (24)
SAPS II
Zero points or normal values were inserted where data were missing [19]. There were no missing variables for physiological data. Among laboratory variables, normal values were inserted for albumin in 623 (49.6%), prothrombin time in 274 (21.8%) and bilirubin in 676 (53.8%) patients. No patient with jaundice on physical examination lacked serum bilirubin measurements
 Soares and Salluh (2006) [39] SAPS II
SAPS 3
SAPS 3 (CSA)
Zero points or normal values were assigned for missing variables [1, 12]. There were no missing data for demographic, clinical and physiologic data. Among laboratory variables, normal values were attributed only for bilirubin in 535 patients (56%). No patient with jaundice lacked bilirubin level measurements
 Soares et al. (2010) [41] MPM III (24)
SAPS II
SAPS 3
SAPS 3 (CSA)
Zero points or normal values were attributed for missing variables.
There were no missing data for demographic, clinical and physiologic data. Missing laboratory variables are depicted in Table 1 of Electronic Supplementary Material [41]. No patient with jaundice lacked bilirubin level measurements
Exclusion and normal value imputation
 Nassar et al. (2012) [42] APACHE IV
SAPS 3
MPM III
3.02% patients with incomplete data which prevented adequate calculation of one or more of the scores were excluded; these missing data could be pre-ICU length of stay, reason for ICU admission, chronic health variables and mechanical ventilation on first day. Missing physiologic variables, namely bilirubin, acid-base abnormalities, PaO2 or PaO2/FiO2 ratio, were considered as normal for purpose of calculations
  1. APACHE Acute Physiology and Chronic Health Evaluation, SAPS Simplified Acute Physiology Score, SAPS (CSA), Simplified Acute Physiology Score (Central and South American), MPM Mortality Probability Models, GCS Glasgow Coma Score, ICU intensive care unit, MICU medical intensive care unit, PaO 2 partial pressure arterial oxygen, FiO 2 fraction of inspired oxygen