There is evidence that around half of the patients prescribed an antihypertensive drug stopping taking it within 1 year. Low adherence is the most common cause of apparent resistant hypertension .
A systematic review and meta-analysis  of interventions to improve medication adherence in hypertensive patients found the largest effect sizes for interventions that:
- Linked patient habits with medication taking.
- Employed motivational interviewing.
- Provided medication in special packaging or pill boxes.
- Encouraged self monitoring.
- Were repeated over several visits, rather than once off.
NICE has produced guidelines to help improve adherence which are available here. They recommend assessing non-adherence by asking the patient if they have missed any doses of medicine recently and making it easier for them to report non˗adherence by:
- Asking the question in a way that does not apportion blame
- Explaining why you are asking the question
- Mentioning a specific time period such as 'in the past week'
- Asking about medicine-taking behaviours such as reducing the dose, stopping and starting medicines.
Tools for addressing adherence include:
- Pointers for discussions on adherence
- New Medicine Service (NMS)
The NMS is a nationally commissioned NHS contractual service aimed at providing support for patients within the first month of starting a new medication. It covers four areas: hypertension, type 2 diabetes, asthma and chronic obstructive pulmonary disease (COPD), and anticoagulation and antiplatelet therapy. The NMS aims to improve patient adherence to long-term medications by encouraging engagement with their new medication.
- The NMS Medicines List Factsheet is available here
A RCT found that after 20 weeks adherence was ten percentage points higher in the intervention (NMS) group (70.7%) than in the control (usual care) group (60.5%) 
How to use the NMS:
- Write on the paper prescription "NMS".
- Or put "NMS" in the free text box of the electronic prescription.
- Remind the patient to ask the pharmacist for a NMS when they give in their prescription.
Addenbrookes hypertension clinic provides update training sessions for practices in hypertension. These can be found here.