Figure 2 Age distribution from 15 global data sets combined versus month attained of 19,949 SIDS [21]. These data in Figure 2 were fit by a 4-parameter lognormal distribution, also known as the Johnson SB distribution [23], shown as (2). Here dp(m) is the probability www.selleckchem.com/products/Lenalidomide.html of SIDS occurring between ages m and m + dm in months, median �� = 3.1 months and standard deviation �� = 0.6617, as fit by maximum likelihood [21] ��exp??[?log?e2([(m+.31)(41.2?��)]/[(41.2?m)(��+.31)])/2��2].?dp(m)dm=(2��2)?1[(m+0.31)?1??+??(41.2?m)?1] (2) Equation (2) can be interpreted as a sum of products of three age dependent terms, denoted as Pn, Pi, and Pa. 3.4. Pn, Risk of Neurological Prematurity Let Pn = 1/(m + 0.31) represent a risk factor of neurological prematurity leading to delays in development of respiratory reflexes and responses, that decreases with increasing age.

Neurological prematurity is a risk factor that is maximal at birth and decreases as the infant physically matures. Kinney [24] has found that an important subset of SIDS appears to have a deficiency in serotonin receptors that is hypothesized as a causal factor of those SIDS. 3.5. Pi, Probability of a Low-Grade Respiratory Infection Let Pi = 1/(41.2 ? m) represent an infection risk factor that increases with increasing age. A low-grade respiratory infection is a risk factor for SIDS. Emery and Weatherall [25] and ?yen et al. [26] discuss a class of infant deaths, sometimes called ��secondary SIDS,�� that have findings of low-grade respiratory infection at autopsy that of itself is insufficient to cause death.

Risk of such infection increases with age as infants lose passively acquired maternal immunoglobulin (IgG) and they have increased exposure to pathogens as they have more contacts both within and without their immediate family. US DHHS [27] linked birth and death certificate data for 1995�C2004 show, in Table 3, that the rate of SIDS increases monotonically with live birth order (LBO). It has been suggested that older school-age siblings may be an important respiratory infection vector [3]. We assume here that the infant lives with two parents, all older siblings survived to the time of SIDS death, and no adoption of the SIDS infant or older siblings took place. For LBO ��6 we assume only 5 siblings have contact with the infant. Table 3 SIDS rate per 1000 live births increases with live-birth order, U.

S. 1995�C2004 [27] as compared to an infection vector model (r = 0.9966). Let the probability of a family member not carrying a respiratory infection AV-951 communicable to the infant at any time = P. For infants with family size = 2 parents + (LBO ?1) siblings the probability of not having an infection vector present is equal P(LBO+1). The probability of an exposure to at least one carrier is then 1 ? P(LBO+1). By least squares analysis we found P = 0.