INTRODUCTION

The diagnosis and management of gout, a diseaseknown since the fifth century BC, is controversial andnot evidence-based. Rigby and Wood,1 in summarisingthe utility of differing diagnostic criteria for gout, statedthat diagnosis is strongly suspected if there is a historyof one or more attacks of podagra/painful joint, in thesetting of hyperuricaemia. Gout is more likely to occurin males with a serum urate > 0.42 mmol/L andfemales > 0.36 mmol/L.

Hyperuricaemia cannot be used as the sole criterionfor diagnosing gout.1 It is estimated that only 20% ofpeople with hyperuricaemia (> 0.42mmol/L), everhave an attack of gout.2

Bellamy, reporting on prescribing practices inAustralia, found that there was a high level ofinappropriate prescribing of allopurinol.3 In particular,prescribing for asymptomatic hyperuricaemia orfollowing a single episode of monoarthritis was verycommon. Demonstration of uric acid crystals andresponse to colchicine therapy are important discrim-inators for the individual patient but are in practicerarely performed.

Treatment with allopurinol, to prevent recurrence ofgout, is efficacious. However, the dose of this drugshould be decreased in the setting of reduced renalfunction, to avoid the allopurinol hypersensitivitysyndrome.4,5 The Australian Adverse Drug ReactionsSystem reported 1118 allopurinol reactions between1972 and 2000.

Renal function deteriorates as a normal process ofageing, declining by 50% between 50 and 90 years of age.6 Creatinine clearance is the ideal measurementof renal function in the elderly.

Our aim was to determine whether the dose ofallopurinol was in accordance with the patient’s esti-mated creatinine clearance (ECC). We were alsointerested to find out how the diagnosis of gout wasmade initially.

METHODS

We carried out the present study at the John HunterHospital (JHH), a 550 bed teaching hospital inNewcastle, New South Wales, after obtaining clearancefrom the Hunter Area Research and Ethics Committee.

The eligible subjects were patients aged 65 years orabove who were discharged on allopurinol over a22-week period. They were identified through the phar-macy department. Patients excluded from the auditwere those with end-stage renal failure and lympho-proliferative disorders.

Data extracted from the records were: age, serumcreatinine, serum urate, dose of allopurinol prescribedand thiazide use. This data allowed an ECC to becalculated using the modified Cockcroft-Gaultequation.7 The prescribed dose of allopurinol was thencross-referenced with the table produced by Hande for allopurinol prescribing in the setting of renalimpairment.5

General practitioners, of 19 patients, were contactedand asked to answer a questionnaire concerning theindividual patients, including the diagnostic procedureused for gout.

RESULTS

Ninety-three patients were discharged from the JHHduring the study period, 49 men and 44 women, withan age range of 65–100 years (mean age 77.7 years).Twenty patients had to be subsequently excluded from further analysis. (Nineteen patients had noweight recorded and in one patient no serum creati-nine was recorded).

The remaining 73 patient records were furtheraudited (Table 1). There was an equal distribution ofmale and female patients with a mean age of 76.7 and77.3 years, respectively. The mean serum creatininewas higher in the women (161 mmol/L) with the mean

J. Qual. Clin. Practice (2000) 20, 42–43

Quality use of Allopurinol in the elderly

PENELOPE SMITH, BMed, NOELINE KARLSON BPHARM, DIP HOSP, PHARM,BALAKRISHNAN R. NAIR, FRCP, FRACP

Department of Geriatric Medicine, John Hunter Hospital, University of Newcastle, Newcastle, NSW, Australia

Abstract Allupurinol is a commonly prescribed drug. However, the use of this drug is not based on evidenceand guidelines. We audited Allopurinol prescriptions in patients aged 65 years and over in a teaching hospital over22 weeks. In 47% of patients the dose was higher than recommended and in 40% it was lower. Quality use ofmedications is an important issue to maintain quality of life in the elderly.

Key words: Allopurinol; elderly; gout; quality use of medications.

ECC lower at 35 mL/min. Serum urate was measuredin seven females and five males; it was raised in fivefemales.

The initial diagnosis of gout by 19 general prac-titioners was examined by questionnaire. The respon-dent number was small. However, the results were inaccordance with the literature, which states that fewpatients have a joint aspiration to confirm the diagnosisof gout. This finding was made despite all respondentsstating they felt confident about aspirating aninflamed/swollen joint. While there was no evidencethat patients had been commenced on allopurinolbecause of an elevated serum urate level alone, therewas evidence that allopurinol was commenced after thefirst attack of podagra. Serum urate level during anattack of joint pain was not always measured.

DISCUSSION

Allopurinol is a commonly used drug. The most com-mon side effect is skin rash but Stevens-JohnsonSyndrome, hepatotoxicity and peripheral neuropathyhave been reported.8 The manufacturers recommenddose reduction according to creatinine clearance.Thiazides are well known to cause hyperuricaemia andprecipitate gout. Increase in hypersensitivity reactionshave been reported when thiazides and allopurinol aretaken together.8

In the present study, the dose of allopurinol washigher than that recommended in 34 patients (47%)and lower in 17 patients (40%) in this audit. Thiazideuse was low at 3%. There is little evidence that medicalpractitioners estimate the individual patient’s creatinineclearance during admission and review the dosage ofallopurinol.

We were unable to estimate a creatinine clearance in19 patients because the patient’s weight was notrecorded. This obviously has implications for thera-peutic decision making. Moreover, there will not be aweight for future reference. The current retrospectivestudy was able to review practice from the patient’srecords, which negated any possible ‘Hawthorne effect’on patient management. It is the only study publishedreviewing diagnosis of gout in the community andallopurinol prescribing. While the study reports onsmall numbers of patients, it shows a trend and the

results should be used as a pilot study for futureresearch in this area.

The findings have implications for both hospital andcommunity medical practice. The diagnosis of goutshould be made in accordance with accepted criteriaand prophylactic therapy should not be prescribedfollowing one attack of a painful joint. Joint aspirationshould be encouraged to detect monosodium uratecrystals and to rule out joint sepsis. A documentedperiodic review of all drugs and dosages for elderlypatients would maximise safety in prescribing. Periodicserum urate and creatinine levels would enable the doseof allopurinol to be reviewed. In the hospital settingwhere therapy is established on admission, an ECCshould be recorded to make appropriate therapeuticdecisions. It is unclear as to whether all of the patientsincluded in the study had gout. Future research in this area must concentrate on refining the diagnosticcriteria. Quality use of medications is an importantissue, which is becoming more important with thechanging demography9.

REFERENCES

1 Rigby AS & Wood PHN. Serum uric acid levels and gout:What does this herald for the population? Clin. ExpRheumatology 1994; 12: 395–400.

2 McGill N. Gout and other crystal arthropathies. Med. J. Aust.1997; 166: 33–8.

3 Bellamy N, Brooks PM, Emmerson BT, Gilbert JR,Campbell J & McCredie M. A survey of current prescribingpractices of inflammatory and urate lowering drugs in goutyarthritis in New South Wales and Queensland. Med. J. Aust.1989; 151: 531–7.

4 Peterson GM & Sugden JE. Educational programme toimprove the dosage prescribing of allopurinol. Med. J. Aust.1995; 165: 74–7.

5 Hande KR, Noone RM, Stone WJ. Severe allolpurinol tox-icity: description and guidelinesfor prevention of patientswith renal insufficiency. Am. J. Med. 1984; 76: 47–56.

6 Roughead EE, Gilbert AL, Primrose JG, Sansom LN. Drug-related hospital admissions: A review of Australian studiespublished 1988–1964. Med. J. Aust. 1998; 168: 405–8.

7 McPherson J. Manual of Use and Interpretation of PathologyTests, 2nd edn. The Royal College of Pathologists ofAustralasia, Sydney, 1997.

8 Prafitt K Martindale: the Complete Drug Reference. WorldColour Book Services, Massachusetts, 1999.

9 Nair B. Older people and medications: What is the rightprescription? Aust. Prescrib. 1999; 22: 130–1.

ALLOPURINOL IN THE ELDERLY 43

Table 1. Allopurinol and renal functions

Patients characteristics (n 5 73) Male Female

Numbers of patients 38 35Age (years) 65–87 (mean 76.7) 66–100 (mean 77.3)Serum creatinine 66–299 (mean 153) 59–398 (mean 161)Estimated creatinine clearance 21–139 (mean 46.2) 11–79 (mean 35)No. serum urate measured 5 (13.0%) 7 (20.0%)No. prescribed diuretics 25 (66.0%) 19 (54.0%)No. prescribed Thiazide diuretic 1 (2.6%) 1 (2.8%)