Written by Anne Fung, M.D.
Global Development Lead, Ophthalmology, Genentech

This is a time of great promise for people living with chronic conditions. Over the past several years, treatment advances have completely shifted the outlook for conditions such as heart disease, diabetes, asthma, and my own area of focus – eye diseases. Thanks largely to better medicines, it’s often possible to reduce symptom burden and improve outcomes to an extent unimaginable just a few decades ago. However, these benefits are only fully realised when treatments proceed as planned. Surprisingly, only about 50% of people with chronic conditions stick to their treatment plans.<sup>1</sup>

In medical terms, this concept of following through with treatment is known as “adherence”. It’s the extent to which a person’s behaviour matches the recommendations they discussed with their doctor (for example around medications and lifestyle changes). Adherence is a dynamic partnership between a doctor and a patient – patients are more likely to adhere to a treatment plan if they are engaged in the process and decisions with their provider, and if they are supported by the wider system.1

Adherence is the single most important factor in achieving the best possible outcomes across all chronic diseases. Good adherence maximises the effectiveness of treatments, and conversely, poor adherence is the number one reason for poor treatment outcomes.1

As a retina specialist, I saw this first-hand in eye diseases like neovascular age-related macular degeneration (nAMD), diabetic retinopathy (DR) and diabetic macular edema (DME). These conditions can lead to severe visual impairment and even blindness, yet it’s entirely possible to avoid such outcomes through a combination of early detection and intervention. In the US alone, 25% of cases of visual impairment are due to treatable eye diseases.2 It’s tragic to know that so many people could be treated for these conditions if only they had access to and sought care from their doctor.

In nAMD, for instance, one in five people are not adherent.3 Among people with DME, underuse of healthcare resources is a well-documented problem, and nearly half of people report not receiving eye-related care in over a year.4 The World Health Organization’s (WHO) ‘Universal eye health: a global action plan 2014-2019’, highlights the critical importance of receiving routine eye examinations and early interventions to minimise vision loss and optimise outcomes among people with eye conditions.5

Given the clear importance of adherence, why does it continue to be such a challenge? The answer is that it’s a complicated issue with many factors at play.

Here are just some of the key factors that can have an impact on adherence, for better or worse:1


Socioeconomic barriers to adherence include limited income, low education levels, unstable living conditions, lack of family or social support, transportation challenges, and misconceptions about disease and treatment.

Healthcare systems

Doctors and nurses, as well as insurers, governments and other local healthcare providers, all have a role to play. Potential issues include a lack of training in chronic disease management and poorly coordinated infrastructure.


Factors related to the disease itself that can affect adherence include the rate of disease progression, symptom severity, and presence of comorbidities.


Even for highly effective therapies, adherence can be impacted by factors including the complexity and duration of treatment, immediacy of benefit, side effects, and previous treatment failures. In ophthalmology, for example, treatment burden is a major issue because certain treatments require frequent doctor visits and injections into the eye.


A person’s attitude, resources, knowledge, beliefs, perceptions and expectations can all affect adherence. Barriers include frustration with the healthcare system, fear of dependence, low expectations, and scepticism about chemicals and biotechnology.

Improving adherence requires the commitment of all stakeholders: patients, healthcare providers, industry, and policymakers.

The WHO recommends focusing on specific interventions to remove adherence barriers, with approaches such as reallocation of health system resources, longer appointment times, information sharing, and ongoing patient-physician communication. In addition, new technologies can be used to educate and pair knowledge with recommended actions.1

At Roche, we’re actively investigating ways to help improve adherence. Our ophthalmology team is especially interested in reducing the treatment burden associated with certain medicines for eye disease.

Sticking with treatment over the course of a chronic disease is no simple task. But it’s crucial given the wide array of effective treatments now available and the growing body of evidence pointing at the importance of adherence. With our combined efforts, we can truly help realise the promise of life-changing medicines for all people with chronic conditions.

This story previously appeared on. (February 2019)


  1. World Health Organization. Adherence to Long-Term Therapies: Evidence for Action. [Internet; cited November 2018].
    Available from:

  2. World Health Organization. Blindness and vision impairment. [Internet; cited November 2018].
    Available from:

  3. Droege KM, Muelther PS, et al. Adherence to ranibizumab treatment for neovascular age-related macular degeneration in real life. Graefe's Archive for Clinical and Experimental Ophthalmology. 2013; 251:1281-1284.

  4. Bressler N, et al. Underuse of the health care system by persons with diabetes mellitus and diabetic macular edema in the United States. JAMA Ophthalmol. 2014; 132:168-173.

  5. World Health Organisation. Universal eye health: a global action plan 2014-2019. [Internet; cited November 2018].
    Available from:

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