2nd June 2017, Volume 130 Number 1456

Treatment of subclinical hypothyroidism or hypothyroxinemia in pregnancy

Subclinical thyroid disease during pregnancy may be associated with adverse outcomes, including a lower-than-normal IQ in offspring. Some advocate that pregnant women with subclinical thyroid deficiency should be treated with levothyroxine during their pregnancy. This paper concerns two trials relevant to this issue.

A total of 677 women with subclinical hypothyroidism and 526 with hypothyroxinemia were randomly assigned to receive levothyroxine or placebo during their pregnancy. Children underwent annual developmental and behavioural testing for five years. The primary outcome was the IQ score at five years of age.

In both trials there were no significant differences noted in the IQ scores at five years of age between those whose mothers had or had not been treated with levothyroxine.

N Engl J Med 2017; 376:815–25

Living near major roads and the incidence of dementia, Parkinson’s disease and multiple sclerosis

Concern is growing that exposures associated with traffic such as air pollution and noise might contribute to neurodegenerative pathology. Emerging evidence suggests that living near major roads might adversely affect cognition. However, little is known about its relationship with the incidence of dementia, Parkinson’s disease and multiple sclerosis.

This report concerns two population-based studies carried out in Ontario, Canada. The multiple sclerosis cohort were aged 20–50 years and the dementia and Parkinson’s cohort were aged 55–85 years. The eligible subjects were free of these neurological diseases at the inception of the study. After 11 years, the researchers noted the incidence of these neurological diseases and associated this with their proximity to major roadways.

In this large population-based cohort, living close to heavy traffic was associated with a higher incidence of dementia, but not with Parkinson’s disease or multiple sclerosis.

Lancet 2017; 389:718–26

Risk of co-treatment with opioids and benzodiazepines

This study reviews the trends in concurrent benzodiazepine/opioid prescribing among privately insured adults in the US and whether there is an association with opioid overdose events.

Between 2001 and 2013, concurrent prescribing of these two drugs increased from 9 to 17%. Co-prescription was associated with an increased risk of an opioid overdose event (odds ratio 2.14).

The researchers concluded that concurrent benzodiazepine/opioid prescribing nearly doubled over this period in this population of privately insured patients in the US and was associated with a significant increase in the risk of opioid overdose.

BMJ 2017; 356:j760