Procalcitonin has little value in diagnosing acute appendicitis, with lower diagnostic accuracy than CRP and WBC. However, procalcitonin has greater diagnostic value in identifying complicated appendicitis. Given the imperfect accuracy of these three variables, new markers for improving medical decision-making in patients with suspected appendicitis are highly desirable.

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Background Age-related alterations in the clinical characteristics and performance of severity scoring systems for community-acquired pneumonia (CAP) are unknown. Methods Consecutive patients with CAP presenting to the emergency department were prospectively studied. Patients were classified as younger adults (age 18e64 years), elderly (age 65e84 years) and very old subjects (age $85 years). Clinical characteristics, complications, outcomes and validity of the pneumonia severity index (PSI) and CURB-65 categories were compared across these three age categories. Results Analysis involved 348 (35.3%) younger adult patients, 438 (44.3%) elderly patients and 201 (20.0%) very old patients. Compared with younger adults, elderly and very old patients had a higher burden of comorbidities and a higher incidence of CAP-related complications. The 30-day mortality rate was 5.2% in younger adults, 7.1% in elderly patients and 9.5% in very old patients. The area under the ROC curve (AUCs) for PSI were 0.87 (95% CI 0.77 to 0.97), 0.85 (95% CI 0.803 to 0.897) and 0.69 (95% CI 0.597 to 0.787) and the AUCs for CURB-65 were 0.80 (95% CI 0.67 to 0.93), 0.73 (95% CI 0.65 to 0.82) and 0.60 (95% CI 0.47 to 0.73) in the younger adult, elderly and very old patients, respectively. A modified PSI or CURB-65 excluding the age variable increased the AUC in most age categories. There was no significant effect of age on 30-day mortality after adjusting for other PSI or CURB-65 variables. Conclusion Elderly patients with CAP have more atypical clinical manifestations and worse outcomes. The underperformance of the PSI in elderly patients may be due to the inappropriate weight given to the age variable. A modification of the cut-off point for PSI or CURB-65 to define severe pneumonia may improve the score performance in elderly patients.

Of the three potentially useful markers, PCT had the best positive likelihood ratio and can be used to confirm the diagnosis of bacterial infections in patients with FN. Due to unacceptably high negative likelihood ratio, medical decision for stopping antibiotics based on PCT alone in this high-risk population may not be possible.

ObjectiveTo examine the diagnostic value of serum B-type natriuretic peptide (BNP) in acute Kawasaki disease (KD).DesignSystematic review and meta-analysis.Data sourcesA systematic literature search strategy was designed and carried out using MEDLINE, EMBASE and the Cochrane Library from inception to December 2013. We also performed manual screening of the bibliographies of primary studies and review articles, and contacted authors for additional data.Study eligibility criteriaWe included all BNP and NT-pro (N-terminal prohormone) BNP assay studies that compared paediatric patients with KD to patients with febrile illness unrelated to KD. We excluded case reports, case series, review articles, editorials, congress abstracts, clinical guidelines and all studies that compared healthy controls.Primary and secondary outcome measuresThe performance characteristics of BNP were summarised using forest plots, hierarchical summary receiver operating characteristic (ROC) curves and bivariate random effects models.ResultsWe found six eligible studies including 279 cases of patients with KD and 203 febrile controls. Six studies examined NT-proBNP and one examined BNP. In general, NT-proBNP is a specific and moderately sensitive test for identifying KD. The pooled sensitivity was 0.89 (95% CI 0.78 to 0.95) and the pooled specificity was 0.72 (95% CI 0.58 to 0.82). The area under the summary ROC curve was 0.87 (95% CI 0.83 to 0.89). The positive likelihood ratio (LR+ 3.20, 95% CI 2.10 to 4.80) was sufficiently high to be qualified as a rule-in diagnostic tool in the context of high pre-test probability and compatible clinical symptoms. A high degree of heterogeneity was found using the Cochran Q statistic.ConclusionsCurrent evidence suggests that NT-proBNP may be used as a diagnostic tool for KD. NT-proBNP has high diagnostic value for identifying KD in patients with protracted undifferentiated febrile illness. Prospective large cohort studies are needed to help determine best cut-off values and further clarify the role of NT-proBNP in the diagnosis process of KD.

Only a few studies have investigated the use of PCT in the diagnosis of bone and joint infection, and these studies have had relatively small sample sizes. We performed a systematic review and meta-analysis of the diagnostic performance of serum procalcitonin (PCT) in the identification of osteomyelitis and septic arthritis in patients who present with fever and orthopedic symptoms. EMBASE, MEDLINE, and Cochrane databases and the reference lists of relevant articles were searched, with no language restrictions, through February 2012. All original studies that reported the use of serum PCT alone or in comparison with other biomarkers for diagnosis of osteomyelitis and septic arthritis were included. Seven studies qualified for inclusion. These studies enrolled a total of 583 patients with suspected bone or joint infection, 131 of whom had confirmed osteomyelitis or septic arthritis. Analysis of the PCT data indicated a bivariate pooled sensitivity of 0.67 (95 % CI: 0.37-0.88), specificity of 0.90 (95 % CI: 0.78-0.96), a positive likelihood ratio (LR+) of 6.48 (95 % CI: 2.28-14.6), and a negative likelihood ratio (LR-) of 0.37 (95 % CI: 0.16-0.84). Use of a lower PCT cut-off value (0.2-0.3 ng/mL) improved the LR + to 6.66 and the LR- to 0.15. Analysis of the three studies that also measured serum C-reactive protein (CRP) indicated that CRP had an LR + of 1.39 (95 % CI: 1.17-1.65) and an LR- of 0.40 (95 % CI: 0.12-1.36). Our results indicate that PCT may be more suitable as an aid for rule-in diagnosis rather than for exclusion of septic arthritis or osteomyelitis and that use of a lower cut-off value for serum PCT may improve its diagnostic performance.

Existing data suggest that PCT tests may add to the diagnosis of sepsis in elderly patients. We did not observe the performance of the PCT test in elderly patients inferior to adult patients. Given the imperfect accuracy, we do not recommend that the PCT test be used in isolation; instead, we suggest that it be interpreted in the context of clinical findings.

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