Incidence of Intussusception as Studied from a Hospital-Based Retrospective Survey over a 10-Year Period (2001^|^ndash;2010) in Akita Prefecture, Japan

Abstract

SUMMARY:One concern about rotavirus vaccines is its possible association with intussusception. Thus, it is necessary to determine the baseline incidence for intussusception in the first year of life in places where rotavirus vaccines are introduced. However, few safety data exist for the period at which the first dose of Rotarix and RotaTeq are allowed to administer in Japan. The first dose of Rotarix is scheduled to administer at 6-20 weeks of age and that of RotaTeq is scheduled to administer at 6-24 weeks of age; the upper limits for these vaccines is later than the upper limit recommended by the World Health Organization by 5 and 9 weeks, respectively. We performed a retrospective cross-sectional study by reviewing medical charts of all hospitals that provided pediatric beds in Akita Prefecture, Japan, and identifying the cases of intussusception that met the Brighton criteria level 1 in these hospitals between January 2001 and December 2010. During this 10-year period, 122 children younger than 1 year of age were diagnosed with intussusception. The incidence of intussusception was estimated at 158 per 100,000 person-years among children younger than 1 year (95z confidence interval, 131-188), 10 per 100,000 person-years for children aged 0-2 months, 165 for children aged 3-5 months, and 300 for children aged 6-8 months. This rapid and substantial increase in the incidence of intussusception during the first year of life should be considered when formulating the immunization schedule for administering rotavirus vaccines in Japan.

A High Incidence of Intussusception Revealed by a Retrospective Hospital-Based Study in Nha Trang, Vietnam between 2009 and 2011

“…A hospital-based study carried out between 1995 and 1999 in Hanoi, Hue, Ho Chi Minh city suggested a frequent occurrence of intussusception in children less than 12 months of age in Vietnam, with cases occurring in the range of 472 to 722 each year [13]. The incidence in Vietnam was considerably higher than in any neighboring country, including Japan with 185 per 100,000 person-years (95% CI: 133–251) [14] or 158 per 100,000 person-years (95% CI: 131–188) [15], Hong Kong with 108 per 100,000 person-years (95% CI: 95.3–119.7) [16], Taiwan with 77 per 100,000 person-years (range 64.2–86.5) [17], Singapore with 22.8–100.8 per 100,000 [18], Thailand with 19.7–47.8 per 100,000 person-years [11] and Malaysia with 17.8 per 100,000 person-years [19]. …”

Systematic review shows that pathological lead points are important and frequent in intussusception and are not limited to infants

“…The incidence has declined in the UK, from 0.86 (1997–1998) to 0.34 (2008–2009) per 1000 live births ; in Australia, New Zealand and the USA, 0.5–2.3 cases per 1000 live births have been reported; and in Japan, 1.8–1.9 per 1000 infants have been reported . Japanese data for 2001–2010 showed an intussusception incidence of 185 per 100 000 person years under the age of one year, with 10 per 100 000 at the age of zero to two months, 165 per 100 000 at the age of three to five months and three per 100 000 at the age of six to eight months .…”

Post‐marketing monitoring of intussusception after rotavirus vaccination in Japan

“…The number of cases expected to occur within 7 and 30 days following vaccination ( Ne ) was derived from the following formula: , where Inc = the incidence of IS cases in the first year of life. The incidence value used for Japan was based on the paper of Noguchi et al (158/100 000 person‐years) Pd i = the proportion of IS cases occurring in the i th month of age.…”

“… Pd i = the proportion of IS cases occurring in the i th month of age. Japanese age‐specific distributions were used Nd i = the number of doses of Rotarix TM distributed in the i th month of age, based on country‐level sales data and an estimate of the age of vaccine administration based on the distribution of age at vaccination spontaneously reported in Rotarix TM cases available in the GSK spontaneous report database. RP = the risk period in days (e.g., 7 or 30 days). 30.4 = the average number of days in a month. …”

“…In Japan, the background incidence of IS is relatively high and ranges between 143.5 and 191 per 100 000 children‐years in the first year of life . This incidence rate is one of the highest in the world, together with other countries, such as Israel (219 per 100 000 children‐years), Vietnam (302), and South Korea (328) …”