Classifying Polypharmacy According to Pharmacotherapeutic and Clinical Risks in Older Adults: A Latent Class Analysis in Quebec, Canada

INTRODUCTION

The simplistic definition of polypharmacy, often designated as the concomitant use of five medications or more, does not distinguish appropriate from inappropriate polypharmacy. Classifying polypharmacy according to varying levels of health risk would help optimise medication use.

OBJECTIVE

We aimed to characterise different types of polypharmacy among older adults and evaluate their association with mortality and institutionalisation.

METHODS

Using healthcare databases from the Quebec Integrated Chronic Disease Surveillance System, we selected a community-based random sample of the population ≥ 66 years old covered by the public drug plan. Categorical indicators used to describe polypharmacy included number of medications, potentially inappropriate medications (PIMs), drug-drug interactions, enhanced surveillance medications, complex route of administration medications, anticholinergic cognitive burden (ACB) score and use of blister cards. We used a latent class analysis to subdivide participants into distinct groups of polypharmacy. Their association with 3-year mortality and institutionalisation was assessed with adjusted Cox models.

RESULTS

In total, 93,516 individuals were included. A four-class model was selected with groups described as (1) no polypharmacy (46% of our sample), (2) high-medium number of medications, low risk (33%), (3) medium number of medications, PIM use with or without high ACB score (8%) and (4) hyperpolypharmacy, complex use, high risk (13%). Using the class without polypharmacy as the reference, all polypharmacy classes were associated with 3-year mortality and institutionalisation, with the most complex/inappropriate classes denoting the highest risk (hazard ratio [HR] [95% confidence interval]: class 3, 70-year-old point estimate for mortality 1.52 [1.30-1.78] and institutionalisation 1.86 [1.52-2.29]; class 4, 70-year-old point estimate for mortality 2.74 [2.44-3.08] and institutionalisation 3.11 [2.60-3.70]).

CONCLUSIONS

We distinguished three types of polypharmacy with varying pharmacotherapeutic and clinical appropriateness. Our results highlight the value of looking beyond the number of medications to assess polypharmacy.

Hormonal response to stress in brittle diabetes

Acute psychological stress may play a role in the glycaemic instability of some patients with type I diabetes through an increased secretion of insulin-counteracting hormones. To examine the validity of this hypothesis, we subjected to a video-recorded public-speaking stress seven healthy persons, six type I diabetics with stable blood glucose levels and six type I diabetics with unstable or brittle diabetes (with more than 10 hypoglycaemia/month and frequent hyperglycaemia). During the test and on a control day, heart rate, blood pressure, plasma ACTH, cortisol, catecholamines and prolactin were measured. The comparison between the stable and unstable diabetics during the stress session by two-way analysis of variance (group/time) showed a significant difference for heart rate, blood pressure, ACTH and cortisol. Psychological interview showed that most unstable diabetics perceived a link between life stress and their blood glucose control. The unstable patients had much more difficulty in verbalizing their emotions. Our study shows that the two groups of diabetic patients display distinct cardiovascular and neuroendocrine responses to psychological stress, as well as distinct psychological profiles. In conclusion, hormonal response to an acute psychological stress is more pronounced in brittle diabetes and might be one of its pathogenic factors.