Vitamin K and childhood cancer

Vitamin K deficiency bleeding (VKDB) in early infancy

Vitamin K deficiency bleeding (VKDB) is a rare and potentially life-threatening bleeding disorder of early infancy. Vitamin K stores are low at birth; thereafter breast-fed infants are at risk because of low concentrations in human milk. Classical VKDB occurs in the first week of life, is related to delayed or inadequate feeding and is readily prevented by small doses of vitamin K at birth. Late VKDB peaks at 3-8 weeks, typically presents with intracranial haemorrhage often due to undiagnosed cholestasis with resultant malabsorption of vitamin K. Diagnosis can be difficult but PIVKA-II measurements can provide confirmation even several days post-treatment. Without vitamin K prophylaxis, the incidence of late VKDB in Europe is 4-7 cases per 10(5) births; it is higher in SE Asia where in rural, low-income areas some 0.1% of affected infants may suffer intracranial bleeding. Late VKDB is largely preventable with parenteral vitamin K providing the best protection. The efficacy of oral prophylaxis is related to the dose and frequency of administration. Most multi-dose oral regimens provide protection for all except a small reservoir of infants with undetected hepatobiliary disease. Targeted surveillance of high-risk groups (e.g. biliary atresia) offers a novel approach to assess efficacy of prophylaxis.

Prevalence of asthma and risk factors among Chinese, Malay, and Indian adults in Singapore

BACKGROUND

The prevalence and morbidity of asthma vary greatly among different ethnic communities and geographical locations, but the roles of environmental and genetic factors are not fully understood. The differences in prevalence of adult asthma among Chinese, Malay, and Indian ethnic groups in Singapore were examined, and the extent to which these could be explained by personal and environmental factors were investigated.

METHODS

A stratified disproportionate random sample (n = 2868) of Chinese (n = 1018), Malays (n = 967), and Indians (n = 883) of both sexes was drawn from households in five public housing estates, and an interviewer administered questionnaire was used to determine cumulative and current prevalence of "physician diagnosed asthma" (symptoms with a physician diagnosis of asthma).

RESULTS

Lifetime cumulative prevalence (standardised to the general population) of "physician diagnosed asthma" was 4.7% in men and 4.3% in women; 12 month period prevalences were 2.4% and 2.0%, respectively. Cumulative prevalence of asthma was significantly higher in Indians (6.6%) and Malays (6.0%) than in Chinese (3.0%); period prevalences of asthma were 4.5% in Indians, 3.3% in Malays, and 0.9% in Chinese. Ownership of cats or dogs was more frequent in Malays (15.4%) and Indians (11.2%) than in Chinese (8.8%). Rugs and carpets were also more frequently used by Malays (52.2%) and Indians (40.7%) than by Chinese (8.9%). Current smoking prevalences were higher in Malays (27.3%) than in Indians (19.4%) and Chinese (23.0%). Malays and Indians did not have higher rates of atopy (11.1% and 15.2%, respectively) than Chinese (15.4%). Adjustment for these factors in multivariate analyses reduced the greater odds of asthma in Malays and Indians, but not to a significant extent.

CONCLUSIONS

There are ethnic differences in the prevalence of asthma in Singapore which are not entirely explained by differences in smoking, atopy, or other risk factors. Other unmeasured environmental factors or genetic influences are likely to account for residual differences in the prevalence of asthma.

Conflicts of interest in research on children

In a research proposal recently submitted to one of the research ethics committees in Wales, children suffering from otitis media, or ‘glue ear’ as it is more familiarly known, were to be tested for allergic reactions to a number of substances using skin-prick tests. Small lancets would be used to pierce the skin of the forearm, allowing the penetration of traces of the allergenic reagent. The size of the subsequent inflamed area of skin would be measured. To demonstrate the expected correlation between glue ear and an allergic reaction, it would be necessary to see whether other children who did not suffer from glue ear also had the same reactions. If they did not, of course, then some causal association between the reaction and the disease condition could be inferred and investigated, with the hope of improving the treatment of the disease itself.

Administration of vitamin K to newborn infants and childhood cancer

OBJECTIVES

To investigate whether childhood cancer is associated with intramuscular administration of vitamin K to newborn infants.

DESIGN

Routines for administration of vitamin K to infants born after normal deliveries during 1973-89 were obtained from maternity hospitals. Occurrence of cancer up to the end of 1991 was identified by comparing these records with the national cancer registry. Adherence to the routine method of administering vitamin K was checked with the medical records of a sample of 396 infants (196 who had developed childhood cancer and 200 controls).

SETTING

All maternity hospitals in Sweden.

SUBJECTS

1,384,424 full term infants born after non-instrumental deliveries, 1,085,654 of whom were born in units where vitamin K was routinely given by intramuscular injection and 272,080 of whom were born where it was given orally.

MAIN OUTCOME MEASURES

Odds ratios for cancer after intramuscular administration of vitamin K versus oral administration after stratification for year of birth.

RESULTS

Adherence to routine method of administering vitamin K was 92% in the 235 cases where individual information could be found. The risk of cancer after intramuscular administration of vitamin K was not elevated compared with that after oral administration: odds ratios of 1.01 (95% confidence interval 0.88 to 1.17) for all childhood cancers and 0.90 (0.70 to 1.16) for childhood leukaemia.

CONCLUSIONS

The alleged association between intramuscular vitamin K prophylaxis to newborn infants and childhood cancer could not be verified in the present study of full term infants born after non-instrumental delivery.

Haemorrhagic disease of the newborn: a review of 127 cases

A review of 127 infants with haemorrhagic disease of the newborn (HDN) is presented. The case definition of HDN used in the selection of patients was bleeding during the 1st week of life in a newborn with normal platelet count, normal peripheral blood smear and complete clinical response to parenteral vitamin K. Equivocal cases with respect to cause of bleeding were excluded. The eligible cases consisted of 0.9% of all admissions to the unit and the male:female ratio was 1.8:1. Most were from families of low economic status and poor educational background. Omission of vitamin K prophylaxis and exclusive breastfeeding were the commonest antecedents. The mean (SE) gestation and admission weight were 39.3 (0.2) weeks and 2981 (78) g, respectively. One hundred and two (80.3%) had classical HDN with a mean (SE) age at onset of 63 (4.4) hours. Gastro-intestinal bleeding was the commonest observation. Thirty-three infants (26%) died, most of them from exsanguination. There is a need for well designed work to determine the magnitude of the problem, including that of late-onset HDN, the antecedent risk factors, the preferred route for administering prophylactic vitamin K and a clear policy guideline on prevention of the disease.