Hemolytic disease and other neonatal jaundice refers to the different etiologies by which a newborn might develop extreme hyperbilirubinemia (EHB), which can in turn become kernicterus.
Neonatal jaundice is a product of total serum or plasma bilirubin (TB) levels rising too high, and has a number of etiologies; Rh disease and glucose-6-phosphate dehydrogenase deficiency (G6PD) are two major ones. In addition to these two, GBD models 'preterm birth' and 'other causes' as etiologies of EHB.
Bilirubin is produced during the breakdown of hemoglobin and other heme-containing proteins. Healthy infants commonly have TB levels of > 1 mg/dL, which increases in the hours after birth.
At lower TB levels, an infant may be diagnosed with benign hyperbilirubinemia, typified by a yellow pigmentation in the newborn caused by the bilirubin. However as TB level increases towards EHB (typically classified as TB > 30 mg/dL), the infant becomes increasingly at risk of bilirubin crossing the blood-brain barrier and binding to brain tissue, resulting in brain damage: bilirubin-induced neurologic dysfunction (BIND).
Hemolytic disease is a product of the mother's immunoglobin G antibodies attacking the fetus or newborn's red blood cells. The main presentations of this condition are RhD hemolytic diseaes and ABO hemolytic disease; however there are over 30 other blood groups, various combinations of which can also result in hemolytic disease.
Glucose-6-phosphate dehygrogenase (G6PD) deficiency is an enzymatic disorder of red blood cells. G6PD is a catalyst in the conversion of NADP to NADPH. NADPH functions to protect red blood cells from oxidant accumulation, which in turn causes cell death.
Preterm birth infants experience a higher rate of EHB than infants born after 37 weeks of gestation. This is caused by a high level of red blood cell turnover in the preterm infant, and thus higher bilirubin levels; a decreased ability to process bilirubin, due to an immature liver; and increased circulation of bile (which contains bilirubin) from the liver to the small intestine (enterohepatic circulation) in preterm infants. Furthermore, while the mechanic is not entirely understood, preterm infants have been observed to have a lower TB threshhold for developing BIND than their full-term counterparts.
We note that in the context of this model, other causes is calculated as the remainder of cases of EHB not attributale to Rh disease, preterm birth, or G6PD. It thus is defined to be all causes of EHB outside of Rh disease, preterm birth, and G6PD.
.. todo:: Describe cause model
There are two possible states for this cause, with-condition for people born with hemolytic disease or other neonatal jaundice, and free-of-condition for people born without hemolytic disease or other neonatal jaundice:
There is no transition between the states; each person is born into one state or the other and permanently stays in that state. Thus, incidence and remission rates are zero.
| State | State name | Definition |
|---|---|---|
| C | With Condition | Simulant was born with haemolytic disease or other neonatal jaundice |
| F | Free of condition | Simulant was not born with haemolytic disease or other neonatal jaundice |
| State | Measure | Value | Notes |
|---|---|---|---|
| C | prevalence | prevalence_c384 | |
| C | birth prevalence | birth_prevalence_c384 | |
| C | excess mortality rate | \frac{\text{deaths\_c384}}{\text{population} \,\times\, \text{prevalence\_c384}} | |
| C | disability weight | \displaystyle{\sum_{s\in \text{sequelae\_c384}}} \scriptstyle{\text{disability\_weight}_s \,\times\, \text{prevalence}_s} | |
| F | prevalence | 1-prevalence_c384 | |
| F | birth prevalence | 1-birth_prevalence_c384 | |
| F | excess mortality rate | 0 | |
| F | disability weight | 0 | |
| All | cause-specific mortality rate | \frac{\text{deaths\_c384}}{\text{population}} |
| Transition | Source State | Sink State | Value | Notes |
|---|---|---|---|---|
| N/A | N/A | N/A | N/A | N/A |
| Variable | Source | Description | Notes |
|---|---|---|---|
| prevalence_c384 | como | Prevalence of hemolytic disease and other neonatal jaundice | |
| birth_prevalence_c384 | como | Proportion of babies born with hemolytic disease and other neonatal jaundice | age_group_id = 164 and measure = 6 (incidence) |
| deaths_c384 | codcorrect | Count of deaths due to hemolytic diseases and other neonatal jaundice | |
| population | demography | Mid-year population for given sex/age/year/location | |
| prevalence_s{sid} | como | Prevalence of sequela with id {id} | |
| disability_weight_s{sid} | YLD appendix | Disability weight of sequela with id {id} |
| Restriction type | Value | Notes |
|---|---|---|
| Male only | False | |
| Female only | False | |
| YLL only | False | |
| YLD only | False | |
| YLL age group start | Early neonatal | age_group_id = 2; [0-7 days) |
| YLL age group end | Post neonatal | age_group_id = 4; [28 days-1 year) |
| YLD age group start | Early neonatal | age_group_id = 2; [0-7 days) |
| YLD age group end | 95 plus | age_group_id = 235; 95 years + |