Hbv Seroprevalence and Risk Assessement

At present, the risk for acquiring hepatitis B virus (HBV) among hospital personnel is high. A cross-sectional analytic study of 380 hospital personnel was conducted in a governmental hospital in Bangkok to investigate HBV sero-prevalence and to assess risk factors in order to develop the risk assessment form for screening the occupational risk of HBV among this group. The studied personnel who had no histories of HBV vaccination and jaundice before working in the hospital were included by voluntary participation. All studied personnel were interviewed by using a structured questionnaire consisted of risk exposure factors and some medical histories. Blood specimens were collected for determining HBV sero-markers (HBsAg, Anti-HBs, and AntiHBc) by an enzyme immunoassay. The risk factors were analyzed by using Odds ratio (OR), χ -test, and multiple logistic regression. The results revealed that 48.68% were positive for any HBV markers. The HBsAg positive rate was 3.42%, anti-HBs ± anti-HBc was 43.16 and 2.11% were positive only anti-HBc. The significant risk factors from univariate analysis were: age over 30 years (OR=3.15, p<0.0001), marital status (OR=2.19, p=0.0002), working in risk ward (OR=2.89, p=0.0274), duration of working over 5 years, (OR=2.81, p<0.0001), a history of accident from working (OR=1.58, p=0.0354), and a history of needle stick (OR=1.83, p=0.0064). After multivariate analysis, the significant risk factors included age over 30 years (OR=2.99, p<0.0001), sex: male (OR=3.05, p=0.0020), working in risk ward (OR=2.81, p=0.0337), and a history of needle stick (OR=2.16, p=0.0030). The risk assessment form was developed by using risk scores. The validity was calculated by the Receiving Operating Curve. The sensitivity of this form was approximately 50% and the specificity was 80% when the cut-off score at risk ≥ 5 was used. In endemic areas including East Asia and Southeast Asia, the transmission of HBV from carrier mothers to their infants has been considered the most important route for HBV infection (Sobeslavsky, 1980; Gust, 1996). While the horizontal transmission including parenteral transmission, sexual contact and close contact with the carrier has been important as well as the mother-to-child transmission in the low and intermediate endemicity (Fay et al, 1985). Previous studies in Thailand showed that HBsAg carrier rate was 5-10% (Pramoolsinsap et al, 1986; Suwanggool et al, 1988). Since the beginning of HBV vaccination among newborn in the year of 1992 was established, the carrier rate has decreased to be 4.30-4.61% during the years 1995-1999 (Khowean et al, 1998; SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Vol 32 No. 3 September 2001 460 Luksamijarulkul et al, 1995). At present, Thailand is an intermediate endemicity of HBV infection. In intermediate and low endemicity of HBV carrier rate, the risk for acquiring HBV among hospital personnel is higher than the risk for general population (Kane et al, 1993; Pruss et al, 1999). In Italy, the incidence of HBV infection among hospital personnel was 3.5 higher than that among general population (Stroffini et al, 1994). This study attempts to investigate HBV seroprevalence and to assess HBV risk factors among hospital personnel in order to develop the risk assessment form for screening the occupational risk of HBV among hospital personnel. It is valuable for preventing HBV infection among this group. MATERIALS AND METHODS Study design and population The study design was a cross-sectional analytic study conducted during October 1997 to March 1998, in voluntary participation of hospital personnel who had no HBV vaccination and no history of illness of jaundice before working in Lerdsin Hospital, a large governmental hospital in Bangkok. Sample size and study methods The sample size was calculated by the formula: n = Z α 2 PQN/Z α 2 PQ+dN. With: N=1,460 hospital personnel, P = proportion of HBV infection rate in health personnel from the previous study = 0.55, Q = 1-P = 0.45, Z α = 1.96 at α = 0.05, d = 0.05; the calculated sample size was 302. The 380 studied hospital personnel who had no HBV vaccination and no history of illness of jaundice before working in the hospital were selected by voluntary participation from 1,460 hospital personnel. All studied personnel were interviewed by a structured questionnaire which was consisted of 3 parts including sociodemographic characteristics, risk exposure factors, and some medical histories. Blood specimens from 380 studied personnel were collected for detecting HBV seromarkers including HBsAg, anti-HBs, and anti-HBc by an enzyme immunoassay (EIA) of which the sensitivity and specificity were 100% and 99.83%, respectively.