Medication underdosing and underprescribing: important issues that may contribute to polypharmacy and poor outcomes

ABSTRACT

Medication underdosing and underprescribing are often overlooked and can result in poor patient outcomes. They can also contribute to polypharmacy and significant cost to the healthcare system. Pharmacists can play a key role in preventing underdosing and underprescribing of medications by ensuring that patient-specific pharmacotherapy is prescribed and administered, and by providing patient and provider education regarding appropriate use of medications. While numerous examples of effective pharmacist-led interventions to reduce medication underdosing and underprescribing are described in the literature, further research is needed to elucidate new ways to improve patient outcomes and reduce unnecessary cost to the healthcare system. This article describes the clinical consequences of medication underdosing and underprescribing and provides examples of pharmacist-led interventions to address these medication issues.

Medication underdosing and underprescribing are often overlooked when considering medication issues that contribute to polypharmacy, poor outcomes, and significant cost to the healthcare system. One study found that 8.8% (95% CI, 4.6–14.9) of drug-related hospital admissions were attributable to subtherapeutic dosing, 16.2% (95% CI, 10.4–23.5) were due to noncompliance, and 8.1% were due to an untreated indication.¹ According to the Agency for Healthcare Research and Quality, the average length of stay and cost for hospitalization in 2010 was 4.7 days and $10,079 per patient.² This is a hefty price to pay when literature suggests that up to 25% of hospital admissions are for drug-related causes and that up to 60% of these adverse drug reactions (ADRs) are preventable.^2,3 This article discusses the scope of the problem and the role of the pharmacist in minimizing medication underdosing and underprescribing.

MEDICATION UNDERDOSING

Medication underdosing occurs when a physician writes a prescription for a lower dose than clinically indicated. One common example of unintentional underdosing is when an antibiotic is administered at a reduced or “renal dose” for a patient who has acute kidney injury. While the dosage is appropriate at the time of prescription, it must be increased once renal function recovers to prevent an inadequately treated condition and possible prolonged hospitalization. Another example is when an inadequate weight-based dose is given due to an inaccurate or outdated weight in the medical record. This can be particularly problematic for patients with fluctuating weights or for pediatric patients. Underdosing may also occur when healthcare providers lower a dosage to minimize adverse effects but do not appreciate the consequences of sub-therapeutic dosing and potential loss of efficacy.

Medication underdosing is not always the result of inappropriate prescribing. Underdosing may also occur when patients take a subtherapeutic dose without the knowledge of their healthcare provider. Possible reasons for this include fear of adverse events, patient economic status, and medication nonadherence.⁴

POLYPHARMACY

Polypharmacy is a potential consequence of medication underdosing because additional medications are often needed to achieve desired therapeutic outcomes. There are many times when polypharmacy is clinically indicated and improves patient care and outcomes; however, inappropriate overprescribing can lead to increases in ADRs and patient non-adherence to complicated medication regimens.^5,6 Some studies report the prevalence of polypharmacy in long-term care facilities to be as high as 40%, which contributes to unnecessary drug cost and adverse events.^7,8 Other risk factors predisposing patients to polypharmacy include having multiple physicians and pharmacies, concurrent comorbidities, impairments in vision or dexterity, and recent hospitalization.⁶

MEDICATION UNDERPRESCRIBING

Underprescribing occurs when there is an untreated indication according to clinical practice guidelines.⁹ Studies suggest that 23% to 64% of patients are underprescribed.¹⁰ This is most common in patients with diabetes mellitus, cardiac disease, or those who live in long-term care facilities.¹⁰ It should be noted that rational underprescribing is possible. One study found that physicians had justifiable reasons for underprescribing in 65% of cases.¹⁰ Interestingly, there is evidence to suggest that patients with polypharmacy are at greater risk for being undertreated for their diseases. A study evaluating 150 geriatric patient records found that of patients with the concomitant use of 5 or more drugs, 42.9% were likely to be undertreated, which was 4.8 (95% CI, 2.0–11.2) times greater than patients prescribed 4 or fewer medications.⁹

Underprescribing can contribute to patient morbidity and mortality as well as significant cost to the healthcare system as a result of hospital admissions and readmissions. For example, evidence suggests that heart failure readmission is more common among patients who are underprescribed for their heart failure (ie, not prescribed an angiotensin-converting enzyme inhibitor [ACEI], angiotensin receptor blocker [ARB], or beta-blocker [BB] at discharge) and among those who are not compliant with medications or follow-up care.¹¹ A recent study found that over half of acutely ill, newly hospitalized patients had at least 1 appropriate medication omitted from their regimen.¹² An interprofessional approach may help to ensure the appropriate administration of medications to patients.

BARRIERS TO MEDICATION OPTIMIZATION

Medication underdosing and underprescribing are often overlooked when considering potential medication issues. Other barriers to optimization of medication regimens include patient and prescriber fear of adverse events, patient nonadherance, inadequate dose adjustments, and poor documentation or miscommunication of medication regimens. Pharmacists are well-positioned to interact with both patients and providers to deliver necessary education to reduce potential medication underdosing and underprescribing. It is important that pharmacy managers find ways to allocate time and resources for these activities.

ROLE OF THE PHARMACIST

Pharmacists can play a key role in evaluating patient medication regimens for appropriateness based on clinical indication and patient-specific factors across all transitions of care. Pharmacists can also provide necessary drug monitoring and patient education regarding the importance of medications and how to correctly take them. This can avoid inappropriate medication use or nonadherence and contribute to better patient outcomes.

There are numerous examples of settings where pharmacists can play a role in proper use and dosing of medications. It is becoming increasingly common for pharmacists to help improve medication use in heart failure clinics where they optimize ACEI, ARB, and BB dosing, resulting in favorable impacts on readmission rates.^11,13 Another example of a pharmacist-led intervention to reduce acute care visits and readmissions is the Pharmacological Intervention in Late Life (PILL) Service at the Veterans Affairs Boston Healthcare System.¹⁴ Through this service, pharmacists identify and resolve medication problems and discrepancies via telephone calls to patients. This resulted in a reduction in emergency/urgent care usage, hospital readmission, and death that was associated with a $312,000 cost avoidance in 1 year.¹⁴ The implementation of antimicrobial stewardship programs also helps to ensure proper utilization, dosing, and monitoring of anti-infective agents.

Inappropriate polypharmacy is also an important medication issue that pharmacists are well positioned to combat. One strategy to reduce polypharmacy is to ensure optimization of monotherapy before adding additional medications.¹⁵ Other strategies include evaluating medication regimens for therapeutic duplications, maintaining accurate medication and medical histories, reconciling medications at each transition of care, linking each prescribed medication to a disease state, and identifying medications that are treating side effects.⁵ A longitudinal study in an outpatient managed care system found that the first instance of drug therapy reviews by a pharmacist reduced polypharmacy by 67.5% and was associated with a $4.8 million reduction in drug cost to the institution.⁶

To help combat underprescription in the elderly population, the Screening Tool to Alert Doctors to Right Treatment (START) has been developed.¹² This tool lists 22 situations in which medications are indicated and suggests that physicians consider initiating treatment in the absence of contraindications. An example of a recommended intervention includes starting an ACEI or ARB in patients with heart failure, diabetic neuropathy, or after acute myocardial infarction. Pharmacists can use this tool to make recommendations to providers for improving patient medication regimens.

FUTURE IMPLICATIONS

Drug underdosing is not listed in the current ICD-9 codes but will be included in the new ICD-10 codes to help identify situations in which a patient has taken less of a medication than prescribed by the physician or instructed by the manufacturer.¹⁶ This will allow for more substantial research into the clinical and financial implications of underdosing and polypharmacy.

CONCLUSION

Medication underprescribing and underdosing can result in adverse patient outcomes including polypharmacy, ADRs, emergency room visits, and hospital admissions. Pharmacists have a role in educating healthcare providers and patients regarding appropriate medication dosing and utilization. Pharmacists can also perform medication reviews and drug monitoring, as well as assist with communicating important information during transitions of care. Pharmacy managers can help ensure that appropriate training and resources are available for pharmacists to fulfill these functions. Future research is needed to elucidate interventions that reduce underdosing and underprescribing and to measure the subsequent impact on patient outcomes.

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Dr Halczli is a PGY-1 pharmacy resident at VA Boston Healthcare System, Boston. Dr Woolley is a clinical pharmacy specialist,VA Boston Healthcare System, and assistant clinical professor, department of pharmacy practice, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston.

The authors have no disclosures to report.