Validating a novel index (SWAT-Bp) to predict mortality risk of community-acquired pneumonia in Malawi.

BACKGROUND: Community-acquired pneumonia is a major cause of mortality worldwide. Early assessment and initiation of management improves outcomes. In higher-income countries, scores assist in predicting mortality from pneumonia. These have not been validated for use in most lower-income countries. AIM: To validate a new score, the SWAT-Bp score, in predicting mortality risk of clinical community-acquired pneumonia amongst hospital admissions at Queen Elizabeth Central Hospital, Blantyre, Malawi. METHODS: The five variables constituting the SWAT-Bp score (male [S]ex, muscle [W]asting, non-[A]mbulatory, [T]emperature (>38°C or <35°C) and [B]lood [p]ressure (systolic<100 and/or diastolic<60)) were recorded for all patients with clinical presentation of a lower respiratory tract infection, presumed to be pneumonia, over four months (N=216). The sensitivity and specificity of the score were calculated to determine accuracy of predicting mortality risk. RESULTS: Median age was 35 years, HIV prevalence was 84.2% amongst known statuses, and mortality rate was 12.5%. Mortality for scores 0-5 was 0%, 8.5%, 12.7%, 19.0%, 28.6%, 100% respectively. Patients were stratified into three mortality risk groups dependent on their score. SWAT-Bp had moderate discriminatory power overall (AUROC 0.744). A SWAT-Bp score of ≥2 was 82% sensitive and 51% specific for predicting mortality, thereby assisting in identifying individuals with a lower mortality risk. CONCLUSION: In this validation cohort, the SWAT-Bp score has not performed as well as in the derivation cohort. However, it could potentially assist clinicians identifying low-risk patients, enabling rapid prioritisation of treatment in a low-resource setting, as it helps contribute towards individual patient risk stratification.

Sepsis carries a high mortality among hospitalised adults in Malawi in the era of antiretroviral therapy scale-up: a longitudinal cohort study.

OBJECTIVE: To assess mortality risk among adults presenting to an African teaching hospital with sepsis and severe sepsis in a setting of high HIV prevalence and widespread ART uptake. METHODS: Prospective cohort study of adults (age ≥16 years) admitted with clinical suspicion of severe infection between November 2008 and January 2009 to Queen Elizabeth Central Hospital, a 1250-bed government-funded hospital in Blantyre, Malawi. Demographic, clinical and laboratory information, including blood and cerebrospinal fluid cultures were obtained on admission. RESULTS: Data from 213 patients (181 with sepsis and 32 with severe sepsis; M:F = 2:3) were analysed. 161 (75.6%) patients were HIV-positive. Overall mortality was 22%, rising to 50% amongst patients with severe sepsis. The mortality of all sepsis patients commenced on antiretroviral therapy (ART) within 90 days was 11/28 (39.3%) compared with 7/42 (16.7%) among all sepsis patients on ART for greater than 90 days (p = 0.050). Independent associations with death were hypoxia (OR = 2.4; 95% CI, 1.1-5.1) and systolic hypotension (OR 7.0; 95% CI: 2.4-20.4). CONCLUSIONS: Sepsis and severe sepsis carry high mortality among hospitalised adults in Malawi. Measures to reduce this, including early identification and targeted intervention in high-risk patients, especially HIV-positive individuals recently commenced on ART, are urgently required.

Severity assessment of lower respiratory tract infection in Malawi: derivation of a novel index (SWAT-Bp) which outperforms CRB-65.

OBJECTIVE: To assess the validity of CRB-65 (Confusion, Respiratory rate >30 breaths/min, BP<90/60 mmHg, age >65 years) as a pneumonia severity index in a Malawian hospital population, and determine whether an alternative score has greater accuracy in this setting. DESIGN: Forty three variables were prospectively recorded during the first 48 hours of admission in all patients admitted to Queen Elizabeth Central Hospital, Malawi, for management of lower respiratory tract infection over a two month period (N = 240). Calculation of sensitivity and specificity for CRB-65 in predicting mortality was followed by multivariate modeling to create a score with superior performance in this population. RESULTS: Median age 37, HIV prevalence 79.9%, overall mortality 18.3%. CRB-65 predicted mortality poorly, indicated by the area under the ROC curve of 0.649. Independent predictors of death were: Male sex, "S" (AOR 2.6); Wasting, "W" (AOR 6.6); non-ambulatory, "A" (AOR 2.5); Temp >38°C or <35°C, "T" (AOR 3.2); BP<100/60, "Bp" (AOR 3.7). Combining these factors to form a severity index (SWAT-Bp) predicted mortality with high sensitivity and specificity (AUC: 0.867). Mortality for scores 0-5 was 0%, 3.3%, 7.4%, 29.2%, 61.5% and 87.5% respectively. A score ≥3 was 84% sensitive and 77% specific for mortality prediction, with a negative predictive value of 95.8%. CONCLUSION: CRB-65 performs poorly in this population. The SWAT-Bp score can accurately stratify patients; ≤2 indicates non-severe infection (mortality 4.4%) and ≥3 severe illness (mortality 45%).

The effect of a tuberculosis chest X-ray image reference set on non-expert reader performance.

OBJECTIVES: In low-resource settings, limitations in diagnostic accuracy of chest X-rays (CXR) for pulmonary tuberculosis (PTB) relate partly to non-expert interpretation. We piloted a TB CXR Image Reference Set (TIRS) to improve non-expert performance in an operational setting in Malawi. METHODS: Nineteen doctors and clinical officers read 60 CXR of patients with suspected PTB, at baseline and using TIRS. Two officers also used the CXR Reading and Recording System (CRRS). Correct treatment decisions were assessed against a "gold standard" of mycobacterial culture and expert performance. RESULTS: TIRS significantly increased overall non-expert sensitivity from 67.6 (SD 14.9) to 75.5 (SD 11.1, P = 0.013), approaching expert values of 84.2 (SD 5.2). Among doctors, correct decisions increased from 60.7 % (SD 7.9) to 67.1 % (SD 8.0, P = 0.054). Clinical officers increased in sensitivity from 68.0 % (SD 15) to 77.4 % (SD 10.7, P = 0.056), but decreased in specificity from 55.0 % (SD 23.9) to 40.8 % (SD 10.4, P = 0.049). Two officers made correct treatment decisions with TIRS in 62.7 %. CRRS training increased this to 67.8 %. CONCLUSION: Use of a CXR image reference set increased correct decisions by doctors to treat PTB. This tool may provide a low-cost intervention improving non-expert performance, translating into improved clinical care. Further evaluation is warranted. KEY POINTS: • Tuberculosis treatment decisions are influenced by CXR findings, despite improved laboratory diagnostics. • In low-resource settings, CXR interpretation is performed largely by non-experts. • We piloted the effect of a simple reference training set of CXRs. • Use of the reference set increased the number of correct treatment decisions. This effect was more marked for doctors than clinical officers. • Further evaluation of this simple training tool is warranted.

Diagnosis of cryptococcal and tuberculous meningitis in a resource-limited African setting.

OBJECTIVES: Cryptococcal meningitis (CM) and tuberculous meningitis (TBM) are common in HIV-infected adults in Africa and difficult to diagnose. Inaccurate diagnosis results in adverse outcomes. We describe patterns of meningitis in a Malawian hospital, focusing on features which differentiate CM and TBM with the aim to derive an algorithm using only clinical and basic laboratory data available in this resource-poor setting. METHODS: Consecutive patients admitted with meningitis were prospectively recruited, clinical features were recorded and cerebrospinal fluid (CSF) was examined. RESULTS: A total of 573 patients were recruited, and 263 (46%) had CSF consistent with meningitis. One hundred and twelve (43%) had CM and 46 (18%) had TBM. CM was associated with high CSF opening pressure and low CSF leukocyte count. Fever, neck stiffness and reduced conscious level were associated with TBM. A diagnostic index was constructed demonstrating sensitivity 83%and specificity 79% for the differentiation of CM and TBM. An algorithm was derived with 92% sensitivity for the diagnosis of CM, but only 58% specificity. CONCLUSIONS: Although we demonstrate features associated with CM and TBM, a sufficiently sensitive and specific diagnostic algorithm could not be derived, suggesting that the diagnosis of CM and TBM in resource-limited settings still requires better access to laboratory tools.