Nearly half of primary care patients were prescribed antidepressants, bisphosphonates, or proton pump inhibitors (PPIs) for longer than necessary, according to findings of a study published in Annals of Family Medicine.
"Legacy prescribing" refers to the prescribing of drugs for a longer period than is typically needed to treat a condition. In the study, it was defined as a period longer than 3 months but not indefinitely. The practice of extended prescribing may contribute to "inappropriate polypharmacy," the taking of multiple medications simultaneously.
The primary care setting is a source of legacy prescribing because it is the coordinating center and gatekeeper for managing patients with multiple morbidities, Dee Mangin, MBChB, DPH, FRNZCG, from McMaster University in Ontario and the University of Otago in Christchurch, New Zealand, and colleagues write. They indicate that legacy prescribing "a key clinical challenge for primary care."
Polypharmacy in general and legacy prescribing in particular raise risks for drug interactions as well as adverse reactions to individual medications. Such effects include falling, poor nutrition, and altered cognition. With more prescriptions to manage daily, patients may face adherence challenges and risk skipping or taking extra doses. Older adults are more likely to experience multiple-medication problems and contribute disproportionately to adverse drug reaction–related hospital admissions in Canada, the researchers write.
Past studies have identified reliance on single-disease guidelines in treating patients with multiple morbidities as a factor in polypharmacy, but legacy prescribing might also be a factor. To investigate this hypothesis, the researchers conducted a population-based retrospective cohort study using prospectively collected data from the McMaster University Sentinel and Information Collaboration Primary Care practice-based research network.
The analysis included 50,813 patients aged 18 years or older seen from 2010 through 2016. The database captured an economically diverse population living in and around Hamilton, Ontario.
For each of the three commonly prescribed drug classes (antidepressants, bisphosphonates, and PPIs), the researchers identified cases in which the prescription duration exceeded the recommended time for treatment, using "conservative...evidence-based inclusion criteria."
For antidepressants, that meant including prescriptions for 15 months or longer when drug treatment is recommended for 6 months after resolution of an acute mood episode. For bisphosphonates, the criterion was continuous prescribing exceeding 5.5 years when osteoporosis treatment is recommended for up to 5 years. For PPIs, the criterion was continuous prescribing for more than 15 months when less than 1 year is typically adequate.
The researchers calculated two "duration criteria" per patient per drug. "Sum duration" measured the sum of the difference in days between the start and stop dates for each drug per patient. The "start-stop duration" was the difference between the first-ever start date and the last-ever stop date for each drug per patient.
After eliminating duplicate or overlapping prescriptions and accounting for outlier patterns such as short-term prescribing for recurrence and time gaps without drug coverage (6 months or longer for PPIs and antidepressants and 1 year or longer for bisphosphonates), use of both sum duration and start-stop duration emerged as the most accurate assessment of legacy prescribing than either alone.
Overall, 11.4% (5806) of the 50,813 patients received legacy prescriptions. Of the total 16,125 prescriptions for the three drug types, 43% (6879) were considered legacy and 44% (7167) nonlegacy.
The proportion of legacy prescriptions by drug class was 46% (3766 of 8119) for antidepressants, 14% (228 of 1592) for bisphosphonates, and 45% (2885 of 6414) for PPIs.
The only association between drugs was that 17% (969 of 5806) of the patients who were given legacy prescriptions received them for an antidepressant and a PPI. The researchers suggest that the concomitant use might reflect a "prescribing cascade" of prescribing a PPI to treat gastrointestinal effects of a selective serotonin reuptake inhibitor. Use of one drug spawns use of another.
Legacy patients tended to be older, and more women than men were prescribed antidepressants and/or bisphosphonates.
At the end of the study, significant proportions of patients were still taking the prescribed legacy drugs: 61% antidepressants, 65% PPI, and 77% bisphosphonates.
"Our findings suggest that legacy prescribing is prevalent, is consistent across prescribers, and could be an important system-level contributor to inappropriate polypharmacy," the researchers conclude. Identifying patients taking legacy prescriptions presents "an opportunity for system-level intervention in primary care with enormous potential benefit for patients."
A limitation of the study was the absence of consideration of the specific details of patients, such as circumstances that might have required unusual prescribing patterns. In addition, the focus on prescribing and not dispensing or patient compliance might have led to an overestimation of drug use duration.
The research was funded by the Pilot Research Project Fund, Department of Family Medicine, McMaster University. The authors have disclosed no relevant financial relationships.
Ann Fam Med. Published online November 12, 2018. Full text
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