Intended for healthcare professionals

Practice Practice Pointer

Using a clinical process map to identify prescribing cascades in your patient

BMJ 2020; 368 doi: (Published 19 February 2020) Cite this as: BMJ 2020;368:m261
  1. Katrina L Piggott, geriatrician and general internist, Mount Sinai Hospital; clinical associate, University of Toronto; MSc candidate, Quality Improvement and Patient Safety, Institute of Health Policy, Management and Evaluation1 4,
  2. Nishila Mehta, medical student, University of Toronto; research assistant, Women’s College Research Institute2 4,
  3. Camilla L Wong, geriatrician, St Michael’s Hospital; associate professor, University of Toronto; project investigator, Li Ka Shing Knowledge Institute3,
  4. Paula A Rochon, vice-president, Research, Women’s College Hospital; senior scientist, Women’s College Research Institute; professor, Department of Medicine and Institute for Health Policy, Management and Evaluation, University of Toronto1 4
  1. 1Department of Medicine and the Institute for Health Policy, Management and Evaluation (IHPME), University of Toronto, Toronto, Canada
  2. 2Undergraduate Medicine, Faculty of Medicine, University of Toronto, Toronto, Canada
  3. 3Division of Geriatric Medicine, St Michael’s Hospital, University of Toronto, Toronto, Canada
  4. 4Women’s College Research Institute, Women’s College Hospital, University of Toronto, Toronto, Canada
  1. Correspondence to: P Rochon paula.rochon{at}

What you need to know

  • Prescribing cascades are a type of problematic polypharmacy that occur when an adverse drug event is misinterpreted as a new medical condition, and a second medication is prescribed or a diagnostic test is ordered

  • Older adults are at higher risk of experiencing prescribing cascades due to the higher incidence of polypharmacy and drug side effects than in younger patients

  • Prescribing cascades increase the pill burden for patients, raise healthcare costs, and cause preventable adverse events

  • One way to identify and reverse prescribing cascades is by creating a clinical process map, a tool designed to illustrate a patient’s presentation, symptoms, medications, possible side effects, and interventions

  • Ask yourself: “Could my patient’s new symptom be caused by a drug they are taking rather than a new medical condition?”

The adverse effects of a drug may “hide” behind common presenting symptoms.1 Prescribing cascades occur when a healthcare provider misinterprets an adverse drug event as a new medical condition and provides a second drug to address the side effect, as described in 1997 by Rochon and Gurwitz in the BMJ.2 The concept has also been expanded to include unnecessary diagnostic tests, medical devices, and over-the-counter therapies,3 which may expose the patient to risk and harm. There is no universally accepted approach to identifying whether a drug is responsible for a symptom, but by identifying prescribing cascades, clinicians can reduce the number of unnecessary medications, investigations, consultations, and harms.

To date, more than 20 prescribing cascades have been identified by cohort and population studies4 (see fig 1 for examples). These prescribing cascades are the result of medications for common conditions such as heart disease, hypertension, obstructive lung disease, diabetes, dementia, and chronic pain.356

Fig 1
Fig 1

Simple clinical process maps of three common prescribing cascades

While prescribing cascades are well documented in the literature, it is not clear why they occur or persist. In our clinical experience, they are challenging to identify for several reasons. Extended life expectancy, multimorbidity, and polypharmacy contribute to disease complexity in older adults, making it difficult for the clinician to discern what is a symptom of illness and what is a drug side effect. If clinicians are not also vigilant in looking for prescribing cascades when new symptoms arise, then certainly they will not be identified. Also, there are time constraints facing most clinicians today, particularly in the outpatient setting, and it can be a time consuming process to screen for prescribing cascades.7 Further, best possible medication histories are often not obtained,8 and practising clinicians and trainees may not adequately question whether patients’ new symptoms could be caused by their current medications.

This article discusses the risks and harms of prescribing cascades before suggesting practical ways in which clinicians can identify them and minimise the potential impact on patients. We propose that clinical process maps (box 1)—a type of workflow diagram that depicts the flow of events in a process—can be used by clinicians as a tool to understand a patient’s medical “big picture,” explore complex presentations, identify prescribing cascades, and improve patients’ health and wellbeing.

Box 1

What are process maps?

Process maps—a standard tool in business and engineering—are a type of workflow diagram used to improve efficiency.9 It depicts the flow of events in a process, and its purpose is to provide insight into a process, identify areas that have gone wrong and can be improved, increase communication, and provide documentation.10


What are the risk factors for prescribing cascades?

Prescribing cascades may occur at any time and in any patient, but the greatest risk is in older adults. Older adults frequently experience multimorbidity, have multiple prescribing physicians, and often receive fragmented healthcare, lacking clear communication as to why a drug was prescribed. As a result, they are up to four times more likely to develop adverse drug events than younger individuals.11

Moreover, many disease-specific guidelines call for an increasing number of medications without recognising the risk of problematic polypharmacy.12 In England, a 2012 report demonstrated that the average number of drugs prescribed for older adults had increased by 53.8% over 10 years, from 11.9 to 18.3 drugs.13 This increase, in turn, was associated with potentially inappropriate prescribing.14

For these reasons, we recommend checking for prescribing cascades, particularly in older adults with multimorbidity, multiple medications, or a multitude of symptoms of unclear aetiology.

Why are prescribing cascades harmful?

Prescribing cascades increase the risk of drug related adverse events. In large, retrospective cohort analyses, they have been associated with the prescription of anticholinergic drugs, syncope, traumatic falls, invasive procedures (such as pacemaker insertion), and drug toxicity in older adults.151617 Prescribing cascades have also been linked to functional decline and hospitalisation.18 In addition, prescribing cascades contribute to patients’ pill burden and increased drug spending.19

The World Health Organization has identified prescribing “Medications without harm” as an international issue.20 Groups worldwide have created different strategies to inform deprescribing of potentially inappropriate medications for adults. These include consideration of prescribing cascades. In addition, the American Geriatrics Society’s 2019 Beers Criteria and the STOPP/START Criteria have updated guidelines to include additional medications recognised for their potential for adverse events and harm in older adults.2122

How might a patient with a prescribing cascade present?

In the example in box 2, the patient experienced a prescribing cascade. Because her healthcare provider did not recognise her diarrhoea as a side effect of her cholinesterase inhibitor, multiple potentially undesirable events followed. She was prescribed potentially unnecessary medications (antidiarrhoeal drugs), underwent potentially unnecessary gastrointestinal investigations, and experienced potentially preventable adverse events, including delirium, which ultimately led to a functional decline.

Box 2

Example of a prescribing cascade

A 71 year-old woman with mild dementia was prescribed a cholinesterase inhibitor. After two weeks, the dose was increased. She developed multiple episodes of diarrhoea and was prescribed antidiarrhoeal medication.

Later that week, she presented to the local emergency department with agitated delirium and was admitted to hospital. The antidiarrhoeal drug was identified as anticholinergic and the cause of her delirium, and was stopped. Her home medications, including the cholinesterase inhibitor, were continued.

She continued to have diarrohea in hospital, which was not recognised as a drug side effect, and she underwent multiple gastrointestinal investigations. Over a prolonged admission, the patient experienced deconditioning and functional decline.


Understanding this sequence of events would have enabled the physician to identify the true source of the diarrhoea, avoid unnecessary gastrointestinal investigations, and reconsider the options for the management of cognitive impairment.

How can prescribing cascades be identified?

The identification of prescribing cascades in real time is challenging. Some resources exist to aid clinicians, including pharmaceutical resources which describe medication side effects and possible drug-drug interactions,23 as well as extensive lists identifying medications that may be harmful in older adults.2122 Helpful brochures can also alert patients to the side effects of medications in order to facilitate a conversation with their provider.24 Finally, there are tools to assist clinicians with deprescribing, including algorithms for weaning drugs25 as well as the NO TEARS checklist, which alerts clinicians to the importance of addressing polypharmacy.26 However, few tools exist that are easy and practical for providers to use at the bedside that specifically address prescribing cascades and that convey a “big picture” understanding of the patient’s medical condition.

One option for identifying and preventing prescribing cascades is by a novel application of process mapping to create a clinical process map. A clinical process map is a graphic representation of a patient’s medical course, demonstrating the temporal relationship between the onset of symptoms and the prescribing of one or more drugs or initiation of medical investigations. One application of this tool is in screening for and identifying prescribing cascades, whereby clinicians can appropriately deprescribe or prevent unnecessary medical interventions. Process maps have previously been used to improve critical thinking27 and specifically with medical diagnostic evaluation.28 The process of mapping a complex presentation allows the “mapper” to visualise the interrelationships between multiple entities, providing opportunity to identify gaps or errors and giving a more holistic understanding of a system in time and space. This is a critical component in identifying prescribing cascades, as the fundamental issue underlying a prescribing cascade is that the clinician fails to recognise the relationship between the drug prescribed and the new symptom in question. Herein lies the critical role for clinical process maps.

Clinical process mapping is a fast and simple process that can be done in an inpatient or outpatient setting, at the bedside while interviewing the patient, or after a clinical encounter.

Figure 2 shows how to produce a clinical process map of a patient experiencing a prescribing cascade. Once completed, you may have a better understanding of your patient’s “big picture.” In addition to assessing alternatives to the drug causing the symptom in question, you can also re-evaluate the need for diagnostic tests and referrals to other healthcare providers to investigate this drug side effect. These tests can be costly and time consuming for patients, and may expose them to unnecessary risks such as radiation, sedative medications, or invasive tests.

Fig 2
Fig 2

How to create a clinical process map of a prescribing cascade, plus an example of a map to investigate whether a prescribing cascade has led to delirium

You may invite your patient and their caregivers to participate in the process map creation. This will help both of you better understand the chronology of the symptoms in relation to the timing of when medications were prescribed. Allied health members may also bring a unique perspective to the mapping process.


With this tool, unnecessary medications, tests, and procedures may be avoided. If prescribing cascades are identified, deprescribing the drug in question may be discussed with the patient. The suspected culprit medication must be evaluated with respect to its original indication and its potential side effects as well as patient preference. As with any medication being deprescribed, it is important to follow up with the patient to determine whether the presenting symptoms have indeed improved or resolved.32 Clinical process mapping may be iterative; it can be reviewed and revised at subsequent visits, thus allowing for further evaluation.

Other benefits of creating a clinical process map

Clinical process maps can also be used as tools for:

  • Teaching healthcare trainees about prescribing cascades

  • Communicating with patients to help them better understand their medications

  • Conveying a “big picture” understanding of the patient’s medical condition to other healthcare providers

Where did we get our information?

We were motivated to write this article after hearing our patients describe their polypharmacy, pill burden, and incidences of taking medications to treat the side effects of other drugs.

We conducted a Medline search of the medical literature with the following search terms: “prescribing cascade,” “polypharmacy,” and “older adults.”

Our recommendations are based on current prescribing and deprescribing guidelines, with additional references drawn from our personal datasets.

Clinical process mapping has been a part of our clinical practice since 2009, and our description of this tool is a reflection on its utility after a decade of use and refinement.

Education into practice

  • Do you routinely review your patient’s medications in detail, especially to determine if they are still indicated?

  • Is your patient taking a medication to treat the side effects of another medication?

  • The last time you ordered diagnostic tests or imaging, or referred your patient to a specialist, could that have been to investigate the side effect of a medication?

  • The last time you felt overwhelmed by a patient’s medical complexity, did you use any strategy or tool to help you see the “big picture” of what’s going on?

How were patients involved in the creation of this article?

We based this article on our clinical experience providing care to older adults in acute care hospitals, long term care homes, and outpatient clinics who have experienced adverse outcomes as a result of prescribing cascades. Members of our research team also interviewed older adults who have experienced prescribing cascades, along with their caregivers.

Based on this extensive clinical experience, it became clear that healthcare providers and patients often do not consider whether a new medical condition could be a medication side effect.

With valuable insights from patients, as well as the engagement of key stakeholders such as pharmacists and clinicians, our group developed a clinical process map tool to help clinicians better recognise and prevent prescribing cascades in their patients.


We acknowledge the contribution of the researchers engaged in patient interviews: Drs Barbara Farrell, Lisa McCarthy, Lianne Jeffs, and Chantalle Clarkin. We thank Dr Jerry Gurwitz for his expertise in this area, Mr Peter Anderson for his assistance in preparing this manuscript, and Dr Nathan Stall and Ms Kate Stern for technical editing.


  • Contributors: All authors made substantial contributions to the article’s conceptual framework and text, and were involved in drafting and revision of the work and in final approval. All authors accept responsibility for the accuracy and integrity of the work. KLP and PAR are the guarantors.

  • Competing interests: We have read and understood the BMJ policy on declaration of interests and have no relevant interests to declare.

  • Provenance and peer review: Commissioned; externally peer-reviewed.