Hyperglycaemia in pregnancy
Gestational diabetes worsens perinatal outcomes but what’s the risk with lesser degrees of carbohydrate intolerance? Evidence has been mixed, and interpretation complicated by varying diagnostic criteria and confounding variables. A study in the NEJM, involving more than 25,000 women, clearly shows that the risk of several adverse outcomes increases smoothly with increasing maternal glucose level, rather than dividing neatly into ‘diabetic’ and ‘not diabetic’. But, as an accompanying editorial points out, the question remains as to what level of glucose is worth treating. As we already treat 43 patients with gestational diabetes to prevent one adverse outcome, the scope for improvement seems limited.
Insulin not required for gestational diabetes
Speaking of which, a study in the same NEJM issue examines whether women with gestational diabetes need insulin, or whether metformin may be equally effective. The study was powered only to rule out a substantial increase in a composite of perinatal complications, and no such overall change was seen. Clinicians will have to decide for themselves whether the slightly lower mean gestational age with metformin is adequately compensated for by factors such as less frequent hypoglycaemia. Unsurprisingly, women preferred a metformin pill over an insulin injection. The bigger question will be how metformin measures up against other oral medications such as glyburide.
Quitting smoking
A study in the BMJ examines whether nortriptyline can help people to stop smoking. Participants (n=901) were allowed to use nicotine patches or not at will, and were given nortriptyline or placebo at random. The results suggest that it doesn’t add much over nicotine replacement alone, with reductions in depression and anxiety but no overall change in withdrawal symptoms, and only a non-significant improvement in cessation at 6 months. An accompanying editorial is reluctant to abandon nortriptyline altogether, pointing out that even a small real improvement in cessation could save large numbers of lives if applied globally. The author’s correction is also worth noting.
Drug-resistant TB
Tuberculosis has been rising in the UK over the last two decades, and the proportion of drug-resistant strains is also increasing, as documented in a paper in the BMJ. Although the increases look fairly modest at first sight (resistance to isoniazid increased from 5% in 1998 to 7% in 2005), an accompanying editorial highlights the increased incidence of resistant cases, which is greater than these changes in proportion might suggest, and the evidence that most multi-drug resistant cases arise from infection with resistant strains, rather than by acquiring resistance from failed treatments. The authors remind us that the best way to fight TB in the UK is to combat it in the areas where it remains endemic, and call for a global perspective.
Which ACE inhibitor?
ACE inhibitors differ in chemical structure, bioavailability, half-life and route of elimination, so it wouldn’t be surprising if some were more beneficial than others. In the absence of head-to-head comparisons, a study in the CMAJ used linked databases to investigate mortality in patients with congestive heart failure treated with these drugs. There wasn’t much to choose between ramipril, lisinopril, fosinopril, quinapril, perindopril or cilazapril, but mortality was slightly higher in those taking enalapril or captopril.
Particulate air pollution
Two years ago, a large observational study from the US showed clear correlations between hospital admission rates for many conditions (especially cardiovascular and respiratory diseases) and recent levels of fine particulate air pollution – particles with aerodynamic diameters of 2.5μm or less. But larger particles (2.5 to 10 μm diameter) turn out to be relatively innocuous. A study in JAMA finds that hospital admissions weren’t associated with levels of coarse particulate matter pollution.
Troponins in heart failure
Cardiac troponins are regulatory proteins of the thin actin filaments of cardiac muscle, whose presence in the circulation is a sensitive indicator of myocardial damage. The diagnostic and prognostic value of troponin measurement is well established in acute coronary syndromes, and a retrospective study in the NEJM shows that it can be useful in acute heart failure too. Of 80,000 people admitted to hospital with acute decompensated left ventricular failure, only about 6% were positive for troponin. But this group had more frequent adverse events, and a doubled mortality, independent of treatment and other prognostic variables.
Better reporting of research
Searching for interesting items to share with his readers, Dr Lydgate scans a lot of medical journals. It’s often a depressing business, with many studies reported so inadequately that a proper critical appraisal is impossible. Does this reflect authors’ ignorance, or are they trying to hide weaknesses in the research? An editorial in PLoS Medicine describes an initiative to drive up standards of reporting with a section called ‘Guidelines and Guidance’. If you don’t yet know about CONSORT, QUOROM, MOOSE, STARD or STROBE, which are the acronyms of checklists to help investigators include essential information when they report RCTs, meta-analyses, diagnostic tests and so on, maybe you should pay them or EQUATOR (Enhancing the Quality and Transparency of Health Research) a visit. Both these sites are open access, so ignorance will no longer wash as an excuse.
