Suboptimal adherence to food restrictions requirements related to drug regimens for chronic diseases

Oral medications for chronic conditions often involve a variety of instructions, including time of day/dosing, drug interactions, and food intake restrictions. However, the extent to which patients follow these instructions is unclear.

We surveyed patients from the US and Europe (UK, France, Germany, Italy, Spain) who were prescribed sulfonylureas (SU: glimepiride, glipizide, or gliclazide) for diabetes or levothyroxine for hypothyroidism. Patients kept a daily diary for 3-5 days documenting their adherence to three criteria: dosing regimen including time of day, warning labels including drug interactions, and food restrictions.

A total of 421 US and 493 European patients took the study medications; 546 patients took SU and 368 took levothyroxine. Overall, 48% of patients were males; 46% were age 65 years or older. Despite most patients having received instructions on medication requirements (US 71%, EU 75%), most patients reported being only somewhat knowledgeable (US 69%; EU 71%). Adherence, measured by the proportion of the days a participant was adherent to each category out of the observational period (ranging from 3-5 days), varied by type of instruction, with the poorest adherence observed for food restriction requirements (US 34% of the observation days, EU 26%) compared to warning labels (US 77%, EU 67%) and dosing regimen (US 85%, EU 87%).

Patients adhered to dosing and cautionary instructions across the majority of the study period but were largely non-adherent to food intake restrictions. Improved communication and increased emphasis on food intake restrictions is needed when advising patients on their medications.