Medication adherence in Spain: figures that reveal an invisible problem

In 2003, the World Health Organization published a sentence that, more than two decades later, remains uncomfortably relevant: "Improving medication adherence can have a greater impact on health than any advance in specific medical treatments." It was not an exaggeration. It was a diagnosis.

Since then, science has advanced enormously. We have better drugs, better diagnostic tests, better clinical guidelines. But there is something that has barely changed: approximately half of patients with chronic diseases do not follow their treatment correctly. And in Spain, the figures are particularly telling.

The scale of the problem

The WHO estimates that in developed countries, average adherence in chronic diseases is around 50%. That means, for every two patients who leave the consulting room with a prescription, one will not follow it as they should. We are not talking about exceptional or disengaged patients. We are talking about the norm.

In Spain, data confirms this trend. Studies carried out by SEFAC (Spanish Society of Family and Community Pharmacy) and CGCOF (General Council of Official Colleges of Pharmacists) place the rate of therapeutic non-compliance between 40% and 60%, depending on the condition and the population studied.

Some specific conditions illustrate the problem well. In cardiovascular diseases — the leading cause of death in Spain — around 50% of patients abandon their treatment during the first year. In type 2 diabetes, between 30% and 50% do not correctly follow the prescribed regimen. In asthma and COPD, the situation is even worse: studies point to non-compliance rates above 60%.

These are not minor conditions. They are diseases where continuity of treatment makes the difference between living well and suffering serious complications. And non-adherence particularly affects patients on polypharmacy, who manage complex regimens with multiple simultaneous medications.

The economic cost: invisible billions

Non-adherence does not only harm the patient. It generates an extraordinary economic impact on the healthcare system. According to data compiled by the OECD, therapeutic non-compliance is responsible for approximately 10% of hospitalisations in Europe. In the Spanish context, this translates into a volume of avoidable healthcare expenditure that various sources place at around 11.25 billion euros per year.

To put it in perspective: each avoided hospital admission represents average savings of between 4,000 and 6,000 euros. When a person with uncontrolled hypertension suffers a stroke, or when a poorly adherent diabetic develops renal complications, the cost of treatment multiplies exponentially. Adherence is not a question of patient discipline: it is a question of system sustainability.

Why it happens: much more than forgetting

We tend to assume that the patient simply forgets to take their medication. And yes, forgetting is a factor. But it is only the surface of a much deeper problem.

Research has identified multiple causes that interact with each other. Regimen complexity is one of the main ones: the more medications, the more different schedules, and the more specific instructions, the greater the probability of error. Patients taking five or more drugs — a common situation among those over 65 — face a daily logistical challenge that is rarely acknowledged as such.

Side effects are another frequent cause of abandonment. The patient does not always consult before stopping medication; they simply stop taking it when the experience of discomfort outweighs the perceived benefit. In asymptomatic conditions such as hypertension, the problem is different but equally insidious: the person does not perceive the effects of the treatment, and therefore does not perceive the consequences of stopping it.

And there is a factor that, despite its importance, is rarely discussed: the lack of follow-up after dispensing. When a patient leaves the pharmacy with their medication, they disappear from the healthcare professional's radar. There is no monitoring, no feedback, no easy communication channel for resolving the everyday questions that arise when taking medication. We analyse this point in depth in our article on why post-dispensing follow-up fails.

What works: the available evidence

It is not all bad news. There is solid evidence on which interventions improve adherence, although the literature also warns that there is no single solution. The most effective strategies combine several approaches simultaneously.

Simplifying therapeutic regimens has a direct impact. Studies have shown that moving from a three-times-daily regimen to a single daily dose can improve adherence by more than 20%. Deprescribing — removing medications that are no longer necessary or whose risk outweighs the benefit — also contributes, especially in patients on polypharmacy.

Pharmacist interventions have proven to be particularly effective. In Spain, programmes such as SEFAC's Pharmacotherapeutic Follow-up service have shown that the active involvement of the community pharmacist can improve adherence by between 10% and 30%, depending on the condition and the intensity of the intervention.

Digital tools add an additional layer: personalised reminders, compliance monitoring, automatic alerts when a non-compliance pattern is detected. But their effectiveness depends on being connected to the healthcare professional. A reminder without professional backing is useful; a reminder integrated into a digital pharmacy follow-up system is significantly more effective.

And we must not forget the role of the informal caregiver. In many households, it is a family member — frequently a daughter or wife — who manages the patient's medication. Equipping them with the right tools and connecting them with the pharmacy multiplies the effectiveness of any other intervention.

The role of community pharmacy

Community pharmacy occupies a unique position in the Spanish healthcare system. With more than 22,000 pharmacies, it is the most accessible point of healthcare: it requires no appointment, it is integrated into the urban fabric, and it maintains frequent contact with the chronic patient that no other professional can match.

This proximity makes it the natural link for detecting adherence problems, resolving doubts in the moment, and providing continuous follow-up. Professional pharmaceutical services — medication review, Personalised Dosing Systems (PDS), adherence programmes — are designed precisely for this. What is lacking in many cases is the digital infrastructure to scale these services beyond physical presence.

Conclusion

The figures are clear. Non-adherence to treatment in Spain is not a clinical curiosity: it is a structural problem with measurable consequences in lives and in resources. And most relevantly, a significant part of that problem is preventable.

We do not need new drugs to solve it. We need better monitoring systems, better communication between patient and healthcare professional, and tools that make adherence something manageable rather than a solitary responsibility of the patient.