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

Validity of Pneumonia Severity Assessment Scores in Africa and South Asia: A Systematic Review and Meta-Analysis

Background: Although community-acquired pneumonia (CAP) severity assessment scores are widely used, their validity in low- and middle-income countries (LMICs) is not well defined. We aimed to investigate the validity and performance of the existing scores among adults in LMICs (Africa and South Asia). Methods: Medline, Embase, Cochrane Central Register of Controlled Trials, Scopus and Web of Science were searched to 21 May 2020. Studies evaluating a pneumonia severity score/tool among adults in these countries were included. A bivariate random-effects meta-analysis was performed to examine the scores’ performance in predicting mortality. Results: Of 9900 records, 11 studies were eligible, covering 12 tools. Only CURB-65 (Confusion, Urea, Respiratory Rate, Blood Pressure, Age ≥ 65 years) and CRB-65 (Confusion, Respiratory Rate, Blood Pressure, Age ≥ 65 years) were included in the meta-analysis. Both scores were effective in predicting mortality risk. Performance characteristics (with 95% Confidence Interval (CI)) at high (CURB-65 ≥ 3, CRB-65 ≥ 3) and intermediate-risk (CURB-65 ≥ 2, CRB-65 ≥ 1) cut-offs were as follows: pooled sensitivity, for CURB-65, 0.70 (95% CI = 0.25–0.94) and 0.96 (95% CI = 0.49–1.00), and for CRB-65, 0.09 (95% CI = 0.01–0.48) and 0.93 (95% CI = 0.50–0.99); pooled specificity, for CURB-65, 0.90 (95% CI = 0.73–0.96) and 0.64 (95% CI = 0.45–0.79), and for CRB-65, 0.99 (95% CI = 0.95–1.00) and 0.43 (95% CI = 0.24–0.64). Conclusions: CURB-65 and CRB-65 appear to be valid for predicting mortality in LMICs. CRB-65 may be employed where urea levels are unavailable. There is a lack of robust evidence regarding other scores, including the Pneumonia Severity Index (PSI).

Acute hypoxaemic respiratory failure in a low-income country: a prospective observational study of hospital prevalence and mortality

INTRODUCTION

Limited data exist on the epidemiology of acute hypoxaemic respiratory failure (AHRF) in low-income countries (LICs). We sought to determine the prevalence of AHRF in critically ill adult patients admitted to a Ugandan tertiary referral hospital; determine clinical and treatment characteristics as well as assess factors associated with mortality.

MATERIALS AND METHODS

We conducted a prospective observational study at the Mulago National Referral and Teaching Hospital in Uganda. Critically ill adults who were hospitalised at the emergency department and met the criteria for AHRF (acute shortness of breath for less than a week) were enrolled and followed up for 90 days. Multivariable analyses were conducted to determine the risk factors for death.

RESULTS

A total of 7300 patients was screened. Of these, 327 (4.5%) presented with AHRF. The majority (60 %) was male and the median age was 38 years (IQR 27-52). The mean plethysmographic oxygen saturation (SpO₂) was 77.6% (SD 12.7); mean SpO₂/FiO₂ ratio 194 (SD 32) and the mean Lung Injury Prediction Score (LIPS) 6.7 (SD 0.8). Pneumonia (80%) was the most common diagnosis. Only 6% of the patients received mechanical ventilatory support. In-hospital mortality was 77% with an average length of hospital stay of 9.2 days (SD 7). At 90 days after enrolment, the mortality increased to 85%. Factors associated with mortality were severity of hypoxaemia (risk ratio (RR) 1.29 (95% CI 1.15 to 1.54), p=0.01); a high LIPS (RR 1.79 (95% CI 1.79 1.14 to 2.83), p=0.01); thrombocytopenia (RR 1.23 (95% CI 1.11 to 1.38), p=0.01); anaemia (RR 1.15 (95% CI 1.01 to 1.31), p=0.03) ; HIV co-infection (RR 0.84 (95% CI 0.72 to 0.97), p=0.019) and male gender (RR 1.15 (95% CI 1.01 to 1.31) p=0.04).

CONCLUSIONS

The prevalence of AHRF among emergency department patients in a tertiary hospital in an LIC was low but was associated with very high mortality. Pneumonia was the most common cause of AHRF. Mortality was associated with higher severity of hypoxaemia, high LIPS, anaemia, HIV co-infection, thrombocytopenia and being male.

Etiology and Risk Factors for Mortality in an Adult Community-acquired Pneumonia Cohort in Malawi

Rationale: In the context of rapid antiretroviral therapy rollout and an increasing burden of noncommunicable diseases, there are few contemporary data describing the etiology and outcome of community-acquired pneumonia (CAP) in sub-Saharan Africa.Objectives: To describe the current etiology of CAP in Malawi and identify risk factors for mortality.Methods: We conducted a prospective observational study of adults hospitalized with CAP to a teaching hospital in Blantyre, Malawi. Etiology was defined by blood culture, Streptococcus pneumoniae urinary antigen detection, sputum mycobacterial culture and Xpert MTB/RIF, and nasopharyngeal aspirate multiplex PCR.Measurements and Main Results: In 459 patients (285 [62.1%] males; median age, 34.7 [interquartile range, 29.4-41.9] yr), 30-day mortality was 14.6% (64/439) and associated with male sex (adjusted odds ratio, 2.60 [95% confidence interval, 1.17-5.78]), symptom duration greater than 7 days (2.78 [1.40-5.54]), tachycardia (2.99 [1.48-6.06]), hypoxemia (4.40 [2.03-9.51]), and inability to stand (3.59 [1.72-7.50]). HIV was common (355/453; 78.4%), frequently newly diagnosed (124/355; 34.9%), but not associated with mortality. S. pneumoniae (98/458; 21.4%) and Mycobacterium tuberculosis (75/326; 23.0%) were the most frequently identified pathogens. Viral infection occurred in 32.6% (148/454) with influenza (40/454; 8.8%) most common. Bacterial-viral coinfection occurred in 9.1% (28/307). Detection of M. tuberculosis was associated with mortality (adjusted odds ratio, 2.44 [1.19-5.01]).Conclusions: In the antiretroviral therapy era, CAP in Malawi remains predominantly HIV associated, with a large proportion attributable to potentially vaccine-preventable pathogens. Strategies to increase early detection and treatment of tuberculosis and improve supportive care, in particular the correction of hypoxemia, should be evaluated in clinical trials to address CAP-associated mortality.

Treating bacterial pneumonia in people living with HIV

Introduction: Bacterial pneumonia remains an important cause of morbidity and mortality in people living with HIV (PLWH) in the antiretroviral therapy (ART) era. In addition to being immunocompromised, as reflected by low CD4 cell counts and elevated HIV viral loads, PLWH often have other behaviors associated with an increased risk of pneumonia including smoking and injected drug use. As PLWH are aging, comorbid conditions such as chronic obstructive pulmonary disease (COPD), cancers, and cardiovascular, renal and liver diseases are emerging as additional risk factors for pneumonia. Pathogens are often similar to those in HIV-uninfected individuals; however, PLWH are at risk for unusual and/or multi-drug resistant organisms causing bacterial pneumonia based, in part, on their CD4 cell counts and other exposures. Areas covered: In this review, we focus on the recognition and management of bacterial community-acquired pneumonia (CAP) in PLWH. Along with antimicrobial treatment, we discuss prevention strategies such as vaccination and smoking cessation. Expert opinion: Early initiation of ART after HIV infection can decrease the risk of pneumonia. Improved efforts at vaccination, smoking cessation, and reduction of other substance use are urgently needed in PLWH to decrease the risk for bacterial pneumonia. As PLWH are aging, comorbidities are additional risk factors for bacterial CAP.

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.

Prognostic indicators in the World Health Organization's algorithm for seriously ill HIV-infected inpatients with suspected tuberculosis

BACKGROUND

Criteria for the 2007 WHO algorithm for diagnosing tuberculosis among HIV-infected seriously ill patients are the presence of one or more danger signs (respiratory rate > 30/min, heart rate > 120/min, temperature > 39 °C, and being unable to walk unaided) and cough ≥ 14 days. Determining predictors of poor outcomes among HIV-infected inpatients presenting with WHO danger signs could result in improved treatment and diagnostic algorithms.

METHODS

We conducted a prospective cohort study of inpatients presenting with any duration of cough and WHO danger signs to two regional hospitals in Cape Town, South Africa. The primary outcome was all-cause mortality up to 56 days post-discharge, and the secondary outcome a composite of any one of: hospital admission for > 7 days, died in hospital, transfer to a tertiary level or tuberculosis hospital. We first assessed the WHO danger signs as predictors of poor outcomes, then assessed the added value of other variables selected a priori for their ability to predict mortality in common respiratory opportunistic infections (CD4 count, body mass index (BMI), being on antiretroviral therapy (ART), hypotension, and confusion) by comparing the receiver operating characteristic (ROC) area under the curve (AUC) of the two multivariate models.

RESULTS

484 participants were enrolled, median age 36, 66% women, 53% had tuberculosis confirmed on culture. The 56-day mortality was 13.2%. Inability to walk unaided, low BMI, low CD4 count, and being on ART were independently associated with poor outcomes. The multivariate model of the WHO danger signs showed a ROC AUC of 0.649 (95% CI 0.582-0.717) for predicting 56-day mortality, which improved to ROC AUC of 0.740 (95% CI 0.681-0.800; p = 0.004 for comparison between the two ROC AUCs) with the multivariate model including the a priori selected variables. Findings were similar in sub-analyses of participants with culture-positive tuberculosis and with cough duration ≥ 14 days.

CONCLUSION

The study design prevented a rigorous evaluation of the prognostic value of the WHO danger signs. Our prognostic model could result in improved algorithms, but needs to be validated.

Pneumonia in the developing world: Characteristic features and approach to management

Community-acquired pneumonia (CAP) is a common cause of morbidity and mortality in adults worldwide, but its epidemiology varies markedly by region. Whilst in high-income countries, the predominant burden of CAP is in the elderly and those with chronic cardiovascular and pulmonary co-morbidity, CAP patients in low-income settings are often of working age and, in sub-Saharan Africa, frequently HIV-positive. Although region-specific aetiological data are limited, they are sufficient to highlight major trends: in high-burden settings, tuberculosis (TB) is a common cause of acute CAP; Gram-negative pathogens such as Klebsiella pneumoniae are regionally important; and HIV-associated opportunistic infections are common but difficult to diagnose. These differences in epidemiology and aetiological profile suggest that modified approaches to diagnosis, severity assessment and empirical antimicrobial therapy of CAP are necessary, but tailored individualized management approaches are constrained by limitations in the availability of radiological and laboratory diagnostic services, as well as medical expertise. The widespread introduction of the Xpert MTB/RIF platform represents a major advance for TB diagnosis, but innovations in rapid diagnostics for other opportunistic pathogens are urgently needed. Severity assessment tools (e.g. CURB65) that are used to guide early management decisions in CAP have not been widely validated in low-income settings and locally adapted tools are required. The optimal approach to initial antimicrobial therapy choices such as the need to provide early empirical cover for atypical bacteria and TB remain poorly defined. Improvements in supportive care such as correcting hypoxaemia and intravenous fluid management represent opportunities for substantial reductions in mortality.

Predictors of in-hospital mortality and length of stay in community-acquired pneumonia: a 5-year multi-centre case control study of adults in a developing country

BACKGROUND

We investigated predictors of in-hospital mortality and length of hospital stay among adults with community-acquired pneumonia (CAP) in Nigeria in order to provide recommendations to improve CAP outcomes in developing countries.

METHODS

This was a multi-centre case control study of patients ≥18 years who were admitted with CAP between 2008 and 2012. Case notes of 100 consecutive patients who died (cases) and random sample of 300 patients discharged (controls) were selected.

RESULTS

Mean ages were 55.4±19.6 (cases) and 49.3±19.2 (controls). Independent predictors of mortality were CURB-65 score ≥3: adjusted odds ratio (aOR) 24.3, late presentation: aOR 8.6, co-morbidity: aOR 3.9, delayed first dose antibiotics (>4 hours): aOR 3.5, need for supplemental oxygen: aOR 4.9, multilobar pneumonia: aOR 4.0, non-pneumococcal aetiology: aOR 6.5, anaemia: aOR 3.8 and hyperglycemia: aOR 8.6. CURB-65 ≥3 predicted mortality with a high specificity (96.1%) but low sensitivity (75%); positive predictive value of 88.2% and negative predictive value of 90.8%. Care in hospital A and B: aOR 3.3 and 2.2 respectively, male gender aOR 2.1, co-morbidity aOR 3.0, anaemia aOR 2.1 and elevated serum creatinine aOR 6.3 independently predicted length of hospital stay >10 days among survivors.

CONCLUSIONS

Several modifiable patient-related and process-of-care factors predicted in-hospital mortality, and length of hospital stay among survivors. Our findings should be used to improve CAP outcomes in developing countries.