Predicting the non-adherent patient

Knowledge about the adherent or non-adherent patient is predominantly sought through analysis of the many factors that are potentially predictive of adherence or non-adherence. These include sociodemographic factors; attitudes and beliefs; the nature and effects of medication; the quality of the doctor-patient relationship; and social isolation and support. This approach has its limitations. Quantifiable, standardised indicators will not capture the complexity of forces at work with each decision-making individual. 

Ironically, the value of some adherence studies may lie precisely in their failure to come up with consistent determinants of adherence or non-adherence. The surprise expressed by researchers when encountering findings contradictory to their expectations amply demonstrates the ease with which assumptions can be made about adherent or non-adherent individuals. The most interesting results are those which challenge common assumptions, such as studies which suggest that peer support increases non-adherence; that those who doubt the therapy's efficacy are better at taking it; or that the more medications you take, the more likely you are to adhere to them.

The lack of predictive findings suggests that specific groups of people (such as drug users or persons who are homeless) should not be presumed a 'bad risk' and excluded from therapy. However, the related conclusion is just as important: that professional assumptions about those who will be adherent are likely to be just as suspect. Studies that pay attention to the patient's own reasons for non-adherence provide insight that is generally missed in quantitative studies. They also point to the importance of adapting daily routines and minimising subsequent disruption to them.

The healthcare team has a responsibility to discuss all treatment options, outline the demands of a particular regimen, discuss potential side-effects and strategies for coping, help the patient figure out ways to integrate taking medication into a daily schedule, problem-solve changes in schedule, and decide with the patient what course of therapy, if any, promises the highest potential for success.

It helps to identify other individuals who can provide support in maintaining adherence, as adherence support needs to continue as long as treatment does. The type of support needed by a patient will probably change over time and caregivers should be aware of this and adjust for it whenever possible.

It is unusual for sociodemographic factors to be associated with adherence to treatment for any chronic illness.¹ In the context of HIV, many studies have looked for a relationship between sociodemographic characteristics and non-adherence, but results have been inconsistent, pointing to the difficulty in predicting non-adherence.

Non-adherence occurs in all groups and classes of people and it is widespread and unpredictable. Furthermore, adherence varies between individuals who share certain sociodemographic features, identities, or behaviours, as well as within the same individual over time.² Adherence is a daily decision, made as an end result of diverse external factors, personal issues, and health beliefs, so it is very hard to generalise, quantify, or make predictions about who will follow a treatment regimen and why.

Although individual studies in a particular setting may find a link between a particular variable and adherence, meta-analyses have failed to turn up consistent associations between adherence and gender, educational level, income level, housing situation, religion, employment, race, ethnicity, minority status, and substance use.

In a number of studies, younger age has been associated with non-adherence.^{3 4} In general, younger persons have a greater sense of invulnerability and this could impact adherence. However, this result is not consistently found in all studies looking at age as a factor.  

Language and cultural barriers within the health system may also contribute to poor adherence, pointing to a need for thorough and precise communication between patients and providers. It is an advantage when healthcare providers and patients share the same first language, but not always a necessity.   

Several studies have looked at the impact of race or minority status on adherence. Unfortunately, it is very difficult to tease out whether differences in response to therapy can be attributed to adherence behaviour, genetic differences, or both.^{5 6} 

Investigators with the US Multicenter AIDS Cohort Study (MACS) looked at levels of adherence in white, black, and Hispanic men and individual factors associated with adherence according to race or ethnicity in over 1100 gay men in the cohort.⁷

They found that black men were 1.4 times more likely than white men to not report 100% adherence. Of those men who identified as European, there was complete adherence in 38%. Full adherence was reported by 28% of black men who identified as African and 13% who identified as Caribbean.

Hispanic men were over twice as likely as white men to not report 100% adherence. Again, those who identified as European had a higher percent reporting complete adherence (44%) than men who identified as being of Central or South American ethnicity (28%) or those from the Caribbean (22%).

For Hispanic men, younger age and high viral load were significantly associated with non-adherence. For white men, younger age, joint pain, and high viral load affected adherence negatively. In black men, financial problems, the cost of prescription drugs, skin rash, and use of crack cocaine negatively impacted adherence. These results led to the sense that interventions to aid adherence should be customised according to race and ethnicity.

A large number of adherence studies are done using quantitative methods. These studies can miss or mask specific adherence problems. Qualitative studies using observation, discussion, interviews etc. to gain insight into adherence barriers will often present a more complete picture of a situation.

Although gender consistently fails to be associated with levels of adherence to HIV, qualitative work on women's experience in maintaining adherence has described gender-specific problems that women face in managing complex treatment regimens, not least the demands of parenting.

A recent US study of over 1200 women found that adherence to therapy was inversely associated with the number of children living at home.⁸ Such problems are invisible when the experience of all women is tested against the experience of all men.

There is a considerable amount of literature focusing on the association of social isolation or social support with treatment adherence. Although these results indicate a general relationship of support to adherence, they do not always provide insight into what kind of support is needed and appropriate. This may well be true, as the amount and type of treatment support will vary according to the treatment setting, the needs of each individual, and those needs over time.

A study of factors that contributed to adherence was conducted in Nigeria, Tanzania, and Uganda. Discussions were held with patients, healthcare providers, and treatment partners to find out how very high levels of adherence are maintained.⁹

The financial and practical barriers to adherence mentioned in other studies conducted in resource-limited areas were also brought up in these interviews. Barriers included needing money for transport to the clinic, food, and sometimes choosing between medicine or food for both the patient and their family.

Researchers learned that because ill health puts a burden on other members of the community, patients are very motivated to maintain good health through good adherence – so as not to become a large burden on others.

In many cases, healthcare providers were willing to assist financially, maintain late hours at the clinic, and/or provide food – with the clear understanding that continued assistance was contingent on taking medication as prescribed. Social networks provided both means and motivation to maintain excellent adherence.

A qualitative study has found that although participants valued social support, especially in overcoming side-effects and the difficulties of taking the drugs, those who provided support can both assuage and create problems. In particular, many participants reported feeling under intense pressure from peers, family and medical providers to take therapy, resulting in a fear of failing to meet expectations and an unwillingness to be open about problems that were encountered.¹⁰ 

In a retrospective cohort study, the impact of depression on clinical outcomes was evaluated for a year following the start of a new antiretroviral regimen. In this cohort, over 1400 persons were diagnosed with depression . Depression was associated with decreased odds of maintaining adherence of 90% or better and of achieving viral load control under 500 copies/ml. Patients who were treated for depression with selective serotonin reuptake inhibitors (SSRIs) had adherence levels and viral control similar to non-depressed patients taking antiretroviral therapy.¹¹