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

BACKGROUND: 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 are differentially aware of and able to follow these instructions is unclear.

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

RESULTS: 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 male; 46% were age 65 years or older. Despite most patients reporting 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%).

CONCLUSIONS: Patients adhered to dosing and cautionary instructions across the majority of the study period but were largely non-adherent to food intake restrictions. One quarter of patients did not receive an in-person consultation regarding their medication requirements, and patient-reported medication knowledge was low across all participants. Improved communication and increased emphasis on food intake restrictions is needed when advising patients on their medications.