Application of logistic regression in combination with multiple diagnostic tests for auxiliary diagnosis of nasopharyngeal carcinoma.

BACKGROUND AND OBJECTIVE: Although there are many markers for the clinical diagnosis of nasopharyngeal carcinoma (NPC), the efficacy of most of the markers for the early diagnosis is poor. This study was to evaluate the diagnostic value of VCA/IgA, EA/IgA, EBV DNA, EBNA1/IgA, EBNA1/IgG and ZTA/IgG for NPC, as well as to screen out an optimized combination using the logistic regression to increase diagnostic accuracy of NPC. METHODS: Eight-one newly pathologically diagnosed NPC patients prior to treatment and 89 health cases from routine physical checkups were entered into the study. Epstein-Barr virus (EBV) DNA was detected by quantitative real-time PCR; VCA/IgA and EA/IgA were assessed by immunofluorescence assays (IFA). The receiver operating characteristic (ROC) curve and the area under the curve were used to evaluate the diagnostic value of a single test or combined tests for NPC, thus to decide the cut-off value. The logistic regression model was used to combine the results from multiple tests to increase diagnostic accuracy. RESULTS: Comparing to the routine parallel sequential test, the logistic regression in combination with multiple diagnostic tests achieved higher diagnostic specificity and sensitivity for NPC. Two optimal combinations were EBV DNA + EBNA1/IgA and VCA/IgA + EBNA1/IgA, whose sensitivity and specificity reached 0.96 and 0.82, 1.00 and 0.84, respectively. When the logistic model was used and the cut-off value was determined by ROC, the sensitivity and specificity of the two combination groups became 1.00 and 0.87, 0.98 and 0.88, respectively. CONCLUSION: Adopting the logistic regression in combination with multiple diagnostic tests and using the probability prediction to decide the cut-off value may help increase the diagnostic sensitivity and specificity for NPC.

[Distribution of hepatitis B virus genotypes and its clinical significance in Guangxi].

OBJECTIVE: To understand the distribution of hepatitis B virus genotype in Guangxi and its clinical significance. METHODS: Nested polymerase chain reaction (nPCR) was used for amplification of HBV DNA in sera of asymptomatic carrier (ASC) of hepatitis B virus (HBV) and patients with different liver diseases from southern and northern Guangxi. Specimens from 161 subjects were positive for HBV DNA and HBV genotype was determined by using restriction fragment length polymorphism analysis, direct sequencing or cloning sequencing. RESULTS: The prevalence of genotype A was 3.7% in all samples and that of genotype B, C and D was 21.7%, 72.7% and 1.2%, respectively. No other genotypes (such as genotype E, F, G, H) were found. The prevalence of genotype C showed an increasing trend in ASC, chronic hepatitis, liver cirrhosis and hepatocellular carcinoma (HCC) group; in contrast, the prevalence of genotype B showed an opposite trend, although no statistically significant difference was observed, except between ASC and HCC (P=0.05). The HBeAg positive rate was higher, and the anti-HBe positive rate was lower in patients with chronic genotype C infection than in those with genotype B (P<0.05 for both). Liver function test (ALT) abnormality was more severe in genotype C group than in genotypes A and B groups having acute or chronic infection (P<0.01 for all comparisons). The prevalence of genotype C in southern Guangxi was higher than that in northern Guangxi. In contrast, the prevalence of genotype B in southern Guangxi was lower than that in northern Guangxi. CONCLUSIONS: 1. The predominant HBV genotypes in Guangxi were genotypes B and C. The major genotype in southern Guangxi was genotype C; while that in northern Guangxi was genotype B, which implied that the distribution of HBV genotype C was consistent with the incidence of HCC in Guangxi. 2. Genotype C maybe associated with development of severe liver diseases including HCC. 3. Genotype A,D and B+C were mostly found in acute, hepatitis and chronic hepatitis group.