Polymerase chain reaction blood tests for the diagnosis of invasive aspergillosis in immunocompromised people.Cochrane Database Syst Rev. 2015 Sep 07CD
Invasive aspergillosis (IA) is the most common life-threatening opportunistic invasive mould infection in immunocompromised people. Early diagnosis of IA and prompt administration of appropriate antifungal treatment are critical to the survival of people with IA. Antifungal drugs can be given as prophylaxis or empirical therapy, instigated on the basis of a diagnostic strategy (the pre-emptive approach) or for treating established disease. Consequently there is an urgent need for research into both new diagnostic tools and drug treatment strategies. Newer methods such as polymerase chain reaction (PCR) to detect fungal nucleic acids are increasingly being investigated.
To provide an overall summary of the diagnostic accuracy of PCR-based tests on blood specimens for the diagnosis of IA in immunocompromised people.
We searched MEDLINE (1946 to June 2015) and EMBASE (1980 to June 2015). We also searched LILACS, DARE, Health Technology Assessment, Web of Science and Scopus to June 2015. We checked the reference lists of all the studies identified by the above methods and contacted relevant authors and researchers in the field.
We included studies that: i) compared the results of blood PCR tests with the reference standard published by the European Organisation for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG); ii) reported data on false-positive, true-positive, false-negative and true-negative results of the diagnostic tests under investigation separately; and iii) evaluated the test(s) prospectively in cohorts of people from a relevant clinical population, defined as a group of individuals at high risk for invasive aspergillosis. Case-control studies were excluded from the analysis.
DATA COLLECTION AND ANALYSIS
Authors independently assessed quality and extracted data. For PCR assays, we evaluated the requirement for either one or two consecutive samples to be positive for diagnostic accuracy. We investigated heterogeneity by subgroup analyses. We plotted estimates of sensitivity and specificity from each study in receiver operating characteristics (ROC) space and constructed forest plots for visual examination of variation in test accuracy. We performed meta-analyses using the bivariate model to produce summary estimates of sensitivity and specificity.
Eighteen primary studies, corresponding to 19 cohorts and 22 data sets, published between 2000 and 2013 were included in the meta-analyses, with a median prevalence of IA (proven or probable) of 12.0% (range 2.5 to 30.8 %). The majority of people had received chemotherapy for a haematological malignancy or had undergone a hematopoietic stem cell transplant. Several PCR techniques were used among the included studies. The sensitivity and specificity of PCR for the diagnosis of IA varied according to the interpretative criteria used to define a test as positive. The mean sensitivity and specificity were 80.5% (95% CI; 73.0 to 86.3) and 78.5% (67.8 to 86.4) for a single positive test result, and 58.0% (36.5 to 76.8) and 96.2% (89.6 to 98.6) for two consecutive positive test results.