Iron to laxative and statin to painkiller led a list of 24 prescribing cascades in older adults

Design

Population-level retrospective cohort, prescription sequence symmetry analysis

Population

2,297,942 community-dwelling adults aged 66 and over, Ontario

Primary outcome

Prevalence, incidence and temporal association of 65 candidate prescribing cascades

Effect

24 cascades prioritised; iron to laxative 11.9% (95% CI 11.7% to 12.1%); corticosteroid to antipsychotic sequence ratio 2.55 (2.47 to 2.64)

A prescribing cascade happens when a drug's side effect is mistaken for a new problem and treated with another drug. This Ontario study examined 65 cascades named by an international expert panel across 2.3 million community-dwelling adults aged 66 and over.

Twenty-four met all three priority criteria: the first drug was common, the cascade was frequent, and the second drug followed the first more often than chance. The most frequent were iron supplement followed by a laxative (11.9% of new iron users), statin followed by an analgesic (10.9%) and cholinesterase inhibitor followed by a sleep medicine (10.3%). The strongest sequence associations were corticosteroid to antipsychotic, laxative to antidiarrhoeal, and cholinesterase inhibitor to antiemetic.

The list is a practical audit tool. When a new prescription is being added for an older patient, it is worth asking whether the symptom started after a recent drug.

• Before prescribing a laxative for an older patient, check whether oral iron was started recently.
• Ask whether new aches began after a statin before adding an analgesic.
• Review a cholinesterase inhibitor when sleep problems or nausea appear after it is started.
• In a patient on steroids who develops agitation, consider the steroid before an antipsychotic.

Why it matters

Every clinician adds prescriptions; this names the commonest ones that may be treating a side effect.

Don't overread it

Prescription data cannot show why a drug was started; some of these sequences will be appropriate care.

The statistics, in plain English

A sequence ratio above 1 means the second drug was more often started after the first than before it; 2.55 means about two and a half times as often. That points to a cascade but cannot prove each case was one.

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