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Diagnosis by numbers - perimenopause

Dr Nick Summerton discusses how to use likelihood ratios in assessing potentially perimenopausal patients

Dr Nick Summerton discusses how to use likelihood ratios in assessing potentially perimenopausal patients

In recent years, biochemistry laboratories have seen a significant rise in requests for hormone profiles to assess whether female patients are approaching the menopause – in other words, whether they're perimenopausal. Patients are now even able to buy such ‘hormone tests' on the internet.

41208392It is important to be able to tell women their menopausal status and provide appropriate advice on symptom management, osteoporosis prevention and the use of hormone replacement therapies. However, laboratory investigations are not as useful as many believe. There is also concern that an inadequate assessment of apparently non-specific symptoms may result in key red flags being missed. For example, urinary symptoms can be related to the menopause – but the combination of these symptoms with bloating and increased abdominal size is found in 43% of women with ovarian cancer presenting to GPs.

For women aged 40 or more, the likelihood ratios for specific items of clinical information indicating that a woman is perimenopausal are detailed in the box below.

Definitions

Likelihood ratio This is the ratio of the probability of an event (such as a symptom) in diseased persons to the probability of that same event in non-diseased persons.

Likelihood ratios indicate how many times more (or less) likely a result is in a patient with the disease compared with a patient free of disease.

The adjectives ‘positive' or ‘negative' indicate whether the likelihood ratio refers to the presence of the clinical information (positive) or the absence of the clinical information (negative).

Positive likelihood ratios with the highest value argue most for disease when the clinical information is present.

Negative likelihood ratios with the value closest to zero argue the most against disease when that clinical information is absent.

Most useful predictors

41208391In general, the best predictors that a woman will reach the menopause within four years are age at least 50 years, amenorrhoea for three to 11 months and menstrual cycle irregularity within the past 12 months.

The likelihood ratios listed in the box indicate that, even on their own, hot flushes are a better discriminator than FSH measurement. Taken together with night sweats, vaginal dryness and self-rating, the total positive likelihood ratio could possibly be as high as 8.5.

Conversely, to rule out the perimenopause, the patient's self-rating had a negative likelihood ratio closer to zero than did FSH measurement.

Dr Nick Summerton is a GP in Yorkshire. This article is based on his book, Patient-Centred Diagnosis, published by Radcliffe Publishing, ISBN 9781846190551

Pulse readers can claim a 15% discount when they buy direct from Radcliffe by telephoning 01235 528820 or online at www.radcliffe-oxford.com by putting PULSEPCD in the discount code box at the checkout.

lrs key A patient's self-rating is one of the most useful parameters A patient's self-rating is one of the most useful parameters

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