RESUMO
<p><b>OBJECTIVE</b>Hepatitis B has been extensively prevalent in China and hepatitis B virus associated nephritis (HBV-GN) has been one of the common renal damages secondary to HBV infection in Chinese children. Regular vaccination against hepatitis B has been carried out nation-wide in China since January 1st, 1992. The present study was conducted to evaluate the effect of regular vaccination against hepatitis B virus on the incidence of childhood HBV-GN and membranous nephropathy (MN).</p><p><b>METHODS</b>Retrospective analysis on the results of renal biopsy in 727 patients (from Nov. 1979 to March 2002) was carried out. The patients were first divided into two groups according to the date when the patients were seen. Group A patients were seen from Nov. 1979 through Dec. 1991; Group B patients were seen from Jan. 1992 through March 2002. Group B patients were further divided into 5 subgroups (Group B(1) to B(5)), with a 2-year interval after 1992. Secondly, each of these groups and subgroups were again divided into two groups, vaccinated and unvaccinated groups.</p><p><b>RESULTS</b>In 727 renal biopsies, 64 cases (8.80%) met HBV-GN diagnostic criteria. Twenty-eight cases were diagnosed as HBV-GN in Group A (211 cases), accounting for 13.27%, while there were 36 cases with HBV-GN in 516 renal biopsies of Group B, accounting for 6.98% (chi(2) = 7.397 and P < 0.01). The frequency in Group B was significantly lower. Prevalence rate (from Group A to Group B(5)) was 13.3% (28/211), 13.0% (9/69), 7.3% (6/82), 6.3% (4/64), 4.9% (4/82), 5.9% (13/219), respectively, which showed a tendency of decline. Only 8 cases of HBV-GN occurred in vaccinated group (231 cases), accounting for 3.5%, while 48 cases of HBV-GN were seen in unvaccinated group (381 cases), accounting for 12.6% (chi(2) = 14.44 and P < 0.001), vaccination history was unknown in 115 of the 727 cases. In 727 renal biopsies, pathological type of 46 cases (6.3%) was membranous nephropathy and all of them had HBV-GN. Six cases of MN occurred in vaccinated group, accounting for 2.60%, while 40 cases with membranous nephropathy were found in unvaccinated group, accounting for 10.5% (chi(2) = 12.92 and P < 0.001). On the other hand, in vaccinated group there still were 8 cases of HBV-GN whose serum markers of HBV were positive. Two of their mothers had apparent evidence of hepatitis B virus infection.</p><p><b>CONCLUSION</b>The frequency of HBV-GN has decreased significantly after vaccination against hepatitis B virus was routinely carried out since 1992; at the same time, childhood membranous nephropathy might be decreasing gradually, too. The cause of individual cases of HBV-GN who has be vaccinated was probably due to maternal-infant transmission and immunization failure. Attention should be paid to interruption of maternal-infant transmission and serological follow-up should be performed in high-risk newborns after vaccination to further lower the incidence of hepatitis B virus associated nephritis.</p>