The epidemiology and healthcare costs of pregnancy-related listeriosis in British Columbia, Canada, 2005-2014

Abstract

Introduction: Listeriosis, a disease caused by the bacteria Listeria monocytogenes, remains relatively rare in Canada. However, the case-fatality rate from listeriosis is high at 20-30%. Listeriosis in pregnancy is of special concern, as the pathogen can be transmitted to the fetus or neonate and cause neonatal infection, spontaneous abortion, stillbirth, and death. This thesis aimed to describe the epidemiologic characteristics, pregnancy outcomes, and direct healthcare costs of pregnancy-related listeriosis in British Columbia, Canada, during 2005-2014. Methods: This secondary data analysis leveraged administrative health and surveillance data from eight databases provided by Population Data BC. The first part of the analysis used descriptive epidemiologic methodology to describe all cases of listeriosis that occurred in pregnant women and neonates during the 10 years. This included the demographic and clinical features of the pregnancy-related listeriosis cases, the proportion of pregnancies that resulted in stillbirth, and the fraction of all stillbirths in British Columbia that can be attributed to listeriosis. The second part of the analysis used a matched cohort design to compare the direct healthcare costs for pregnant women and neonates with and without listeriosis. Healthcare utilization and unadjusted costs per type of healthcare use were summarized descriptively. A generalized linear model with a gamma distribution and log-link was also used to model highly skewed cost data, adjusted for several variables. Results: There were 10 lab-confirmed and an additional 1-5 potential cases of listeriosis in pregnant women. There were 1-5 lab-confirmed and an additional 1-5 potential cases of neonatal listeriosis. Pregnant women with confirmed listeriosis had a median gestational age at listeriosis onset of 31 weeks and on average, gave birth pre-term (median of 34 weeks). Neonates with listeriosis had a median birthweight of 2,915g, which was lower than the average birthweight in British Columbia, and experienced complications at birth such as meningitis and sepsis. Between 10-50% of confirmed pregnant women with listeriosis had a stillbirth and the fraction of stillbirths that can be attributed to listeriosis was between 0.048% and 0.239%. Pregnant women and neonates with listeriosis had significantly more hospital visits, days in hospital, and physician visits on average than those without listeriosis. Pregnant women with confirmed listeriosis on average had 2.48 times higher mean total healthcare costs than those without listeriosis, adjusted for age, health authority, and income quintile (p<.0001). Neonates with confirmed listeriosis on average had 14.48 times higher mean total healthcare costs than neonates without listeriosis, adjusted for sex, income quintile, and presence of a congenital abnormality (p<.0001). Conclusion: Between 2005 to 2014, pregnancy-related listeriosis in British Columbia was rare. Some pregnant women did experience stillbirth but no neonates died. All maternal cases experienced pregnancy complications and all neonatal cases experienced birth complications. Pre-term delivery among pregnant women and low birth weight among neonates were common. Furthermore, compared to pregnant women and neonates without listeriosis, healthcare costs were on average significantly higher for pregnant women and neonates with listeriosis. This study has highlighted important information for public health specialists, clinicians, and policy makers.