Journals Watch: Hip implants and dementia

Not had the time to read all of the journals? Let Dr Bryan Palmer update you on the latest research.

Failure rates of metal-on-metal THR were found to be too high (Photograph: SPL)
Failure rates of metal-on-metal THR were found to be too high (Photograph: SPL)

Failure rates of metal-on-metal hip implants
Lancet 2012 doi:10.1016/S0140-6736(12)60353-5

Total hip replacement (THR) is extremely common. Some prostheses fail, particularly in younger patients, and need to be revised, most commonly for loosening secondary to wear or dislocation. Surgeons have tried to address these problems by implanting large diameter metal-on-metal bearing surfaces. Does it make a difference?

The authors analysed the National Joint Registry of England and Wales for primary hip replacements undertaken between 2003 and 2011 and found that metal-on-metal THR failed at high rates. Failure was related to head size, with larger heads failing earlier.

Five-year revision rates in younger women were 6.1% for 46mm metal-on-metal compared with 1.6% for 28mm metal-on-polyethylene. By contrast, ceramic-on-ceramic articulations involving larger head sizes were associated with improved survival.

The authors concluded that metal-on-metal stemmed articulations should not be implanted and that those in place should be carefully monitored.

Treating moderate to severe Alzheimer's disease
N Engl J Med 2012; 366: 893-903

Treating mild to moderate Alzheimer's disease (AD) with cholinesterase inhibitors is now a well-accepted (although at times controversial) practice. What is not known is whether treatment benefits continue after progression to moderate to severe disease.

This British study, supported by the Medical Research Council and the Alzheimer's Society, assigned 295 patients to one of the following regimens for 52 weeks: continue donepezil, discontinue donepezil, continue donepezil and start memantine or discontinue donepezil and start memantine.

Alzhemier's disease: study authors concluded that continued treatment with donepezil in patients with moderate or severe AD was associated with cognitive benefits

There was a clinically significant change on standardised mini mental state examination (MMSE) for those who continued donepezil of 1.9 compared with those who discontinued treatment. Standardised MMSE was also higher (1.2 on average) for those on memantine compared with no memantine. However, adding memantine to donepezil gave no additional benefit over donepezil alone.

The authors concluded that continued treatment with donepezil in patients with moderate or severe AD was associated with cognitive benefits that exceeded the minimum clinically important difference, and with significant functional benefits over 12 months.

Cases of diabetic retinopathy identified through screening
BMJ 2012; 344: e874

When I left the UK in 2006, the QOF was paying GPs to organise annual retinal screening in diabetic patients, while the routine interval in Australia was two years. Now it seems the UK might be reconsidering its annual interval based on this study carried out in Wales.

Researchers reviewed 57,199 people with type 2 diabetes mellitus diagnosed at age 30 or older, who showed no evidence of diabetic retinopathy at their first screening between 2005 and 2009. Cumulative incidence of any retinopathy was 360.27 per 1,000 people; incidence for referable retinopathy was 11.64 per 1,000.

Incidence of referable retinopathy was independently associated with known duration of diabetes, age at diagnosis and use of insulin; 10 years of insulin treatment increased the referable incidence to 31 per 1,000.

The authors say their analysis supports extending the screening interval beyond the currently recommended 12 months, with the possible exception of those who have had diabetes for 10 years or more and who are on insulin.

Efficacy and safety of DPP-4 inhibitors for type 2 diabetes
BMJ 2012; 344: e1369

This study assessed the efficacy and safety of DPP-4 inhibitors compared with metformin as monotherapy, or with other commonly used hypoglycaemic drugs combined with metformin, in adults with type 2 diabetes.

The review of RCTs included 27 reports of 19 studies including 7,136 patients randomised to a DPP-4 inhibitor and 6,745 patients randomised to another hypoglycaemic drug. Primary outcome was the change in HbA1c. Secondary outcomes included all-cause mortality and side-effects.

Diabetes: study examined the efficacy and safey of DPP-4 inhibitors on type 2 diabetes

Compared with metformin as monotherapy, DPP-4 inhibitors were associated with a smaller decline in HbA1c. As a second-line treatment, DPP-4 inhibitors were inferior to GLP-1 agonists but similar to pioglitazone in reducing HbA1c, and gave no advantage over sulfonylureas in achieving target HbA1c.

Incidence of nausea, diarrhoea and vomiting was higher in patients receiving metformin or a GLP-1 agonist than in those receiving a DPP-4 inhibitor. Risk for nasopharyngitis, URTI or UTI did not differ between DPP-4 inhibitors and any of the active comparators.

For the cost, lack of long-term safety data and end-point data you might reconsider your prescribing habits, but ask yourself this: if these drugs had come out first would you be using glitazones and sulfonylureas?

Combination treatment for hypertension in diabetes
Clin Ther 2012 doi: 10.1016/j.clinthera.2012.02.004

Hypertensive patients with diabetes often require combination therapy to achieve target BP. The aim of this eight-week randomised, parallel-group, double-blind trial was to investigate whether the single-pill combination of telmisartan and amlodipine was superior to amlodipine alone as initial therapy in patients with diabetes and hypertension.

Once-daily treatment with telmisartan 80mg plus amlodipine 10mg (T/A) was compared with once-daily amlodipine 10mg (A).

After eight weeks, 71.4% of patients who were in the T/A group achieved a target BP <140/90mmHg, versus 53.8% of those in the A group.

The more stringent target of <130/80mmHg was achieved by 36.4% and 17.9% of patients in the T/A and A groups, respectively. The most common adverse events were peripheral oedema, headache and dizziness.

No surprise, but the study also suggests that to achieve the target of 130/80mmHg, patients will require at least three medications.

Reflect on this article and add notes to your CPD Organiser on MIMS Learning

  • Dr Palmer is a former Hampshire GP currently working in Australia, and a member of our team who regularly review the journals

These further action points may allow you to earn more credits by increasing the time spent and the impact achieved.

  • Invite a specialist to talk to the practice about medication options in AD.
  • Review your patients with diabetes, with the aim of targeting those who have not had a recent retinal screen for follow-up.
  • Discuss and set up a practice protocol for the drug management of hyperglycaemia in type 2 diabetes.

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