Potentially Inappropriate Medications, Drug Interactions Common in Geriatric Cancer

Geriatric adults with cancer often have multiple comorbidities and therefore are frequently prescribed multiple medications. A study published in the Journal of Geriatric Oncology examined the prevalence of potentially inappropriate medications (PIMs), severe drug interactions (SDIs), and their associated risk factors among older adults.

An aging population has led to increased rates of cancer, which is frequently one of several complex diseases being dealt with simultaneously in this population. Therefore, it is increasingly important for oncologists to consider multiple factors as they treat cancer, including:

• The evidence base for the treatment of older adults
• The potential for cancer treatments to interact with other co-morbidities, medications, and patients' functional and cognitive status
• The appropriateness of treating cancer in the context of other conditions

Polypharmacy, defined as 6 or more medications, is reportedly as common in older adults without cancer as it is in those with cancer. Pitfalls like potentially inappropriate prescribing and adverse drug reactions can leader to increased health care resource utilization. In this study, researchers also identified rates of major polypharmacy, defined as 11 or more medications.

The study took place over 1 year at 2 large hospitals that serve approximately 800,000 in the Republic of Ireland. The Screening Tool of Older Persons' Prescriptions (STOPP) and OncPal criteria were used to identify PIMs. STOPP criteria include drugs prescribed without an evidence-based clinical indication and any drugs prescribed beyond the recommended duration. OncPal is a deprescribing tool that was designed to identify and assist deprescribing in cancer patients with a limited life expectancy. Stockley's interaction checker identified the potential SDIs.

The 12-month observational study aimed to identify PIMs in cancer patients 65 years and older. It was part of a larger prospective observational study assessing the prevalence, predictability, and preventability of ADRs in cancer care overall. In all, 186 patients with a mean age of 72 years were enrolled.

The mean number of comorbidities was 7.5, and multimorbidity (more than 2 chronic conditions) was identified in 100% of patients. A total of 79% of patients had 5 or more chronic conditions. The most common cancer diagnoses were lung (23.1%), breast (11.8%) and colorectal (11.3%). The most common non-cancer diagnoses were anemia (68.3%), hypertension (57%), and dyslipidemia (50.5%)

In total, 1283 medications were prescribed to 178 participants, 95.7% of the overall group. The median number of prescribed drugs per patient was 7. Polypharmacy and major polypharmacy were identified in 113 (60.8%) and 33 (17.7%) patients, respectively. Of the 186 patients, 60.2% (112) were prescribed systemic anticancer therapies (SACTs). A total of 42 (22.6%) were concomitantly receiving radiation therapy. Non-cancer prescriptions most commonly included proton pump inhibitors (58.6%), statins (40.3%), beta blockers (33.3%), opioids (30.6%), and anti-platelets (28%).

Where STOPP criteria are concerned, 136 participants (73.1%) were prescribed at least 1 PIM. The median was 2, with a range from 0-7. Patients who were prescribed more than 1 PIM had significantly more comorbidities. For each additional prescription, the odds of receiving a STOPP PIM increased by 79.2%.

Researchers reported that 81.8% of patients had been prescribed at least 1 PIM, according to OncPal criteria. With each additional prescription, the odds of being prescribed an OncPal PIM increased by 38.2%. The authors noted that despite 41.4% of patients dying within 6 months of enrollment, 81.8% of patients had been prescribed at least 1 OncPal PIM. “Many of the drugs listed within this tool are preventative treatments, and prescribing them in the last months of life is unlikely to be beneficial and may pose increased iatrogenic risk,” they wrote.

Of the 186 participants, 50.5% (94) had at least 1 potential SDI. This included 7.5% with potential SACT-SACT SDI, 10.2% with potential SACT-other drug SDI, and 41.4% with at least 1 potential drug-drug SDI. These patients with potential SDIs were more likely to have more chronic conditions and be prescribed more medicines. These patients were also more likely to have died within 6 months of enrollment, and the odds of a potential SDI increased by 50.8% with each additional medication.

One study limitation was the fact that one physician alone did the PIM assessment, although the physician was a senior geriatrician with a particular interest in geriatric pharmacotherapy.

The authors concluded that in older patients with cancer, high rates of multimorbidity, PIMs and SDIs are common. Specialist evaluation by a geriatrician may help identify PIMs before adverse reactions occur.

“Older adults with cancer may benefit from a comprehensive medication review by a specialist geriatrician with expertise in clinical pharmacology (including an extensive knowledge of chemotherapeutic agents), experience with managing multimorbidity, and a clear understanding of cancer illness in this population,“ the authors concluded. “… Structured medication reviews in older multi-morbid patients with cancer represent an important element of optimal treatment of these patients.”

Reference

Lavan A, O’Mahoney D, O’Mahony D, Gallagher P. Potentially inappropriate medication (PIM) use and severe drug interactions (SDIs) in older adults with cancer. J Geriatr Onc. Published online February 26, 2021. doi:10.1016/j.jgo.2021.02.021