| pA2 online © Copyright 2004 The British Pharmacological Society |
172P
University of Newcastle Winter Meeting December 2004 |
Thiazide diuretic prescribing and hyponatraemia in primary care patients J. A. Clayton1, S. Rodgers2, A. Avery3 & I. P. Hall1. 1Division of Therapeutics and Molecular Medicine, University Hospital, Queen’s Medical Centre, Nottingham, 2Trent Focus, Division of Primary Care, University Park, Nottingham, and 3Division of Primary Care, University Hospital, Queen’s Medical Centre, Nottingham, UK. |
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Print abstractThiazide diuretics have been used in the management of hypertension for over 50 years and continue to be recommended as one of the first line agents in the treatment of essential hypertension [1]. Hyponatraemia is a well documented and potentially life threatening side effect of thiazide diuretic treatment [2, 3]. Inpatient studies suggest that it is a common side effect, occurring in 11% [4] and 33% [5] of geriatric admissions taking a thiazide. Inpatients frequently have co-morbidity and the risk of hyponatraemia in primary care, where thiazides are most frequently prescribed, is unknown.
The aim of this study was to investigate the pattern of thiazide prescribing and frequency of hyponatraemia in a primary care setting.
A cross sectional observational study of patients aged 18 years and over from six UK General Practices was performed using the MIQUEST (Morbidity Information Query and Export SynTax) computer software programme. This software tool searched and extracted data from the electronic patient records (EPR) of each practice over a 12 year time frame (1990 to 2002).
Thirty-two thousand two hundred and eighteen patients were studied, of these 3773 (11.7%) had received at least one thiazide prescription. Detailed prescribing data were available for 2942 patients, age range 19–99 years (median 68 years) of whom 1965 (66.8%) were female. Of these 989 (33.6%) had a recorded sodium concentration. The median sodium concentration was 138 mmol l-1, (range 110 mmol l-1–147 mmol l-1, with a negative skew (–1.987)). 130 (13.1%) patients had a sodium concentration below the normal range; 35 (3.5%) were below 130 mmol l-1, with nine of these falling below 125 mmol l-1.
Thiazide diuretics were frequently prescribed in primary care. The majority of patients prescribed a thiazide did not have a computer-recorded check of their electrolytes. In those where electrolyte levels had been recorded hyponatraemia was common, occurring in 13.1%. In the majority of cases it was mild but moderate or severe hyponatraemia was seen in 3.5%. The use of a routine check of serum sodium concentration after thiazide initiation should be explored as a means of reducing the morbidity and mortality associated with this adverse drug reaction.
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