Chapter 4 A CONCEPTUAL MODEL FOR TB ADHERENCE FACTORS
4.2 Knowledge Acquisition
4.2.1 Existing TB Adherence Factors Categorization Models
Several categorizations of factors contributing to adherence behaviour have been published [8], [1], [28]. These earlier studies carried out an assessment of the factors for the purpose of providing a better understanding of the relationship between the factors and patients’ adherence, and for proposing appropriate intervention strategies. The studies include a World Health Organization (WHO) study[1], a systematic review and study by Munro et al [8], and a quantitative literature review by Jin et al [28].
These three studies present dimensions for categorizing influencing factors. Additional categorization concepts that are not evidence-based, but nonetheless are useful for categorizing influencing factors, have been proposed, e.g. temporal variation proposed by Castelnuovo [39], and Kruk et al [40].
4.2.1.1 The World Health Organization Model
A study by WHO was aimed at structuring appropriate intervention plans for several infectious and chronic diseases [1]. This is the earliest known attempt to consolidate knowledge about the influencing factors for comprehensive intervention plans for different types of diseases. The study draws on several qualitative and quantitative studies to present a categorization that was then used to propose disease-
specific intervention approaches. It presented a conceptual model that includes two dimensions for classifying factors that influence adherence behaviour of several chronic disease patients, including TB and HIV/AIDS [1].
Firstly, the factors were grouped into five major categories. These are: patient-related, socio-economic, health system, therapy-related and condition-related.
Patient-related: This category is based on the characteristics and demographic attributes of patients, such as gender, marital status and age group
Socio-economic: This category contains all social or economic factors, such as stigmatization, social support network, employment status, poverty and transportation cost
Health system: This is a group of factors that result from poor healthcare services, practices and policies that have an effect on patients’ adherence. It includes the behaviour of healthcare workers, unfavourable opening hours of the healthcare facility and unavailability of drugs
Therapy-related: This is the category of factors that are directly related to medication and treatment taken by patients. It includes factors such as medication side effect, symptom persistence and long treatment duration.
Condition-related: This category is based on circumstantial behaviour, such as abuse of substances, alcoholism, emotional states and personal beliefs of patients
Secondly, two categories were presented, based on the type of effect: positive factors, which stimulate patients to adhere more, and negative factors that cause a decrease in adherence [1].
4.2.1.2 Jin et al’s Model
Jin et al [28] identified some categorizations for representing influencing factors through a systematic review of 102 articles that focused on all types of therapy for several chronic and infectious diseases.
The study focused on all types of therapy for several chronic and infectious diseases. A literature search was conducted on the Medline database using medical subject headlines that indicate non-adherence to treatment and their influencing factors. The search was streamlined by means of an age restriction on
patient population and, more importantly, using the context of the study. Only articles focusing on identifying the influencing factors were included.
The study examined common factors causing therapeutic non-adherence from the patient’s perspective and identified three dimensions for classifying these factors: factor type, types of effect and impact measurement difficulty.
Firstly, they presented five categories based on factor type: patient-centred, therapy-related, healthcare system, social and economic, and disease-related.
Patient-centred: is a collection of demographic and psychosocial factors, including age, ethnicity, gender beliefs, literacy, substance abuse and compliance history
Therapy-related: is a collection of factors that are peculiar to the disease treatment process, including treatment complexity, duration of the treatment period and medication side effects
Healthcare system: represents the group of factors associated with the failure of a healthcare provider to meet treatment requirements, leading to poor adherence by patients. It includes lack of accessibility long waiting time and unhappy clinic visits
Social and economic: represents all socio-economic circumstances that make it difficult for patients to adhere to treatment, including inability to take time off work, cost and income, and social support
Disease-related: represents factors relating to patients’ experiences of diseases that translate into a belief that results in adherence or non-adherence to treatment. Persistence and severity of disease symptoms are typical factors under this category
Secondly, they presented three categories based on the type of effect: compliance increment, compliance decrement and no-effect. Compliance increment refers to the group of factors that improve patients’ adherence. Compliance decrement implies the group of factors that motivate poor adherence.
Where there is neither an increase nor a decrease in compliance to treatment, the factor is regarded as a no-effect.
Thirdly, they presented two categories based on difficulties encountered in measuring the effect and counter-intervention of the factors. They are hard factors and soft factors. Hard factors are those whose impact is more quantifiable and can be addressed to an extent through counselling and communication.
Soft factors are those whose effects are difficult to counter and measure. Soft factors are interrelated and dependent on other factors. However, the study has no clear classification of factors under these categories.
4.2.1.3 Munro et al’s Model
Munro et al [8] conducted a systematic review of the literature from 1999 to 2005 and developed a model for categorizing influencing factors. The review was aimed at understanding which factors are considered important by TB patients, caregivers and healthcare providers.
The focus of this study is the factors that influence TB patient adherence. A search was carried out on electronic databases for qualitative studies using the terms adherence, concordance and compliances are used as keywords for the search. The literature was further screened with pre-specified inclusion criteria that were provided by an expert in the domain. A total of 44 articles drawn from different regions of the world were reviewed. From the study, four main categorization themes were developed.
Eight relevant themes were pre-identified for both patient and caregiver's perspectives and were used to determine the relevance of the selected studies for the review. These themes are organization of treatment and care for TB patients, interpretation of illness and wellness, financial burden, knowledge, attitudes and beliefs about treatments, law and immigration, personal characteristics and adherence behaviour, side effects, and family, community and household influence.
Munro et al developed a model for categorizing factors that influence TB patient adherence behaviour which consists of four main themes: structural factors, personal factors, social context factors and health service factors.
Structural factors: These are factors that exist in society over which a patient has little personal control. These factors relate to economic, social, policy-related, organizational or other aspects of the environment
Personal factors: These consist of a group of factors based on the choices and beliefs of the patient shaped by the psychological and physiological impact of diseases and by the social and cultural structures surrounding the patient. They include motivations, knowledge, beliefs, attitudes and interpretation of wellness and illness
Social context factors: These consist of factors that relate to the social situation of the patient under treatment. They includes factors such as the support from the patient’s family in fighting against the reproaches of the disease, the attitude of family members - either positive or negative, and the availability of a strong social network in the community to support patients
Health service factors: These are factors that emanate from poor healthcare services or failure of the healthcare system. They include factors such as unavailability of drugs and the patient experiencing difficulties in consulting healthcare providers.
Munro et al also classify the factors according to the region where the studies were carried out.
Countries and continents are the geographical areas that were used to stratify the studies included in the review. The highest number of studies included in the review was from Africa, followed by North America, South America and East Asia.
4.2.1.4 Castelnuovo’s Temporal Variation: Phase of Treatment
Two categories were identified through a review of six studies carried out by Castelnuovo [39] to depict the period of effect of factors. The categories relate to the treatment phases of an anti-TB treatment plan. The first is the intensive phase, which is the first two months of anti-TB treatment after the patients are diagnosed with TB. The second is the continuation phase, which starts immediately after the intensive phase and continues for four to six months [39]. Other temporal representations are the weekly and monthly categorizations introduced by Kruk et al [40] who reviewed 14 studies that focused on the timing of default in low income countries’ TB treatment.