Can Fine Needle Aspiration Cytology be Used as a "Proxy Gold Standard" to Diagnose Tuberculous Mastitis?

OBJECTIVE: To assess the performance of fine needle aspiration cytology (FNAC) in the diagnosis of tuberculosis mastitis. MATERIALS AND METHODS: Diagnostic test performance evaluation using two methods-as compared to an alloyed gold standard as well as in the absence of a gold standard. Alloyed gold standard combined the results of acid fast bacilli in cytology smears, histopathological confirmation, and response to treatment. Bayesian estimation of test parameters was done in the absence of the gold standard. RESULTS: FNAC was carried out in 6,496 consecutive cases of breast lump and 104 cases of granulomatous mastitis were detected. Both methods of test parameter estimation identified a high specificity of FNAC for the diagnosis of tuberculosis mastitis (98.9% and 98.4%, respectively). Estimation of sensitivity was falsely high (100%) using the alloyed gold standard because of a workup bias and falsely low (8.41%) using the Bayesian estimation because of low prevalence. Likelihood ratios by both methods suggested that FNAC has good discriminatory capability. CONCLUSION: In situations where prevalence of tuberculosis is high and where facilities for histopathological evaluation do not exist, FNAC can offer an optional alternative to base the therapeutic decision for starting antitubercular treatment.

Predictive performance of anthropometric indexes of central obesity for the risk of type 2 diabetes.

BACKGROUND: In spite of several available anthropometric indexes, the relative merit of these indexes for the prediction of type 2 diabetes remains unknown. Considering that obesity and diabetes commonly coexist as co-morbidities, our objective was to directly compare the performance of measures of central and general obesity to predict the risk of type 2 diabetes. METHODS: We conducted a case-control study of type 2 diabetes on 150 cases and 150 age- and gender-matched controls. We directly compared the predictive performance of five anthropometric indexes: four related to central obesity--waist circumference (WC), waist/hip ratio (WHR), abdominal volume index (AVI) and conicity index (CI); and one related to general obesity--body mass index (BMI). We used various statistical approaches like area under (AUC) receiver-operating characteristic (ROC) curves, likelihood ratios, logistic regression and Shannon's entropy to compare the performance of the indexes in the study sample as well as bootstrapped samples. RESULTS: WC had the highest overall predictive accuracy that was gender insensitive (AUC=0.77 in males and 0.74 in females); a comparable information content as that of AVI (Shannon's entropy=1.81 for WC and 1.84 for AVI) and was a better predictor of the risk of type 2 diabetes than all the remaining indexes. WC also correlated strongly with the biochemical markers of diabetes like blood sugar and lipid profile. CONCLUSIONS: WC is a simple, non-invasive and accurate predictor of the risk of type 2 diabetes that can potentially be used in screening programs in developing countries.

Platelet distribution width (PDW) is increased in vaso-occlusive crisis in sickle cell disease.

Considering the multigenic and multifactorial nature of the disease, we argue that a generalized bone marrow hyperplasia-and not merely erythroid hyperplasia-will occur in sickle cell disease. Consequently, we expect the hematological parameters to depict erythroid, myeloid as well as megakaryocyte hyperplasia. In the light of this expectation, we hypothesized that platelet distribution width (PDW) will increase in sickle cell disease. Here, we report the results from a cross-sectional study of 216 children admitted with complaints suggestive of vaso-occlusive crisis. We observed a strong association between PDW and sickle cell disease as compared to children who had HbAA genotype. Our findings bridge previous inconsistencies relating to the role of platelets in sickle cell disease. Implications of this finding are discussed.

Comparative study of fine needle aspiration and fine needle capillary sampling of thyroid lesions.

OBJECTIVE: To investigate whether fine needle capillary (FNC) sampling gives quantitatively and qualitatively superior cytologic material as compared to the conventional technique of fine needle aspiration (FNA) when performed by a single aspirator. STUDY DESIGN: Cross-sectional diagnostic test evaluation study. FNA and FNC were performed by a single operator on 200 diffuse and nodular thyroid lesions. RESULTS: A statistically significant difference in favor of FNC was observed for the parameter amount of cellular material. For the rest of the parameters--background blood or clot, degree of cellular degeneration, degree of cellular trauma and retention of architecture--the average score favored FNC but was not statistically significant--i.e., smears prepared from FNC displayed cellular material that was more concentrated, less damaged and less likely to be obscured by blood. CONCLUSION: Although FNC sampling was diagnostic in a greater number of cases than FNA sampling, this study did not prove a clear superiority of FNC over FNA. Until greater experience shows clear sampling superiority of FNC alone, rather than performing only FNA in diffuse or nodular thyroid lesions, incorporating FNC into the second puncture will definitely improve the quality and quantity of material at the patient's first visit.