Drug use and side effects in the elderly : findings from the Kungsholmen project

Abstract

The aim of this thesis was to find occurrence of drug side effects in the elderly by studying the association between changes in clinical parameters and prevalence of self-reported symptoms and the use of drugs in an elderly population. The studies were performed in the Kungsholmen project, a longitudinal population based study of aging and dementia in Stockholm. Data from baseline (1987-89), 1st follow-up (1991-93), 2nd follow-up (1994-96), and 3 d follow-up (1997-98) were used. The first two articles describe crosssectional studies examining the prevalence of low blood pressure (Paper 1) and sodium and potassium disturbances (Paper 11) with respect to medication (baseline, n=1748 and 1558). The third paper examined the association between drug use and hyperglycemia, as measured by increased HbA1c levels (2 nd follow-up, n=578). The fourth article is a longitudinal (6 years follow-up) study of age-related impairment of renal function in connection to drug use (baseline to 3rd follow-up, n=242). The fifth article examines the use of antidepressants and anxiolytics in relation to self reported somatic and psychiatric symptoms (3rd follow-up, n=419). The most important results are summarized below.

Study I: The use of potassium-sparing diuretics, dopaminergic antiparkinsonian drugs and neuroleptics were significantly associated with low systolic blood pressure and dopaminergic antiparkinsonian drugs with low diastolic blood pressure.

Study II: The occurrence of hyponatraemia was associated with the use of carbamazepine, laxatives (enema), diuretics and ACE-inhibitors and hypernatraemia with osmotically active laxatives. Hypokalaemia was associated with thiazide-related and combination diuretics and hyperkalaemia with potassium-sparing diuretics, beta-blockers, cytostatic drugs and tricyclic antidepressants.

Study III: Use of loop diuretics was significantly associated with high HbA1c levels in both women and men. Eighteen percent of users had high levels compared with 8% in non-users.

Study IV: The prevalence of renal impairment, defined as estimated creatinine clearance (CE) <50 ml/min, was 33 % at baseline and 93 % in 3rd follow-up. The use of drugs that should be avoided or be prescribed in reduced doses in mild or moderate renal insufficiency increased over time, with few exceptions. Doses decreased for digoxin, spironolactone and allopurinol, but increased for drugs against peptic ulcer, ACE-inhibitors and citalopram.

Study V: Elderly treated with antidepressants showed a high total score on the Comprehensive Psychopathological Rating Scale (CPRS) (23.6±10.9) and score for depressive symptoms (6.4±7.2). The scores were even higher for users of anxiolytics (26.3±23.2 and 7.6±14.4). The use of antidepressants was significantly associated with several somatic symptoms such as vertigoldizziness, tendency to fall, involuntary urination, and shortness of breath. The use of anxiolytic drugs was associated with vertigo/dizziness and shortness of breath.

Conclusions: Side effects of drugs occur frequently in an elderly population and with many drugs that are generally not considered in clinical practice. There is a continuous age-related loss of renal function. However, apparently physicians often do not adjust the treatment according to this very important age-related physiological change, which in turn increases the risk of side effects. Our results also indicate ineffective and inappropriate treatment of depression as well as side effects of anxiolytic and antidepressant therapy in the elderly.