Understanding non-adherence in medical contexts

Non-adherence refers to situations where patients do not follow medical advice or treatment plans as recommended by healthcare professionals. This can include missing doses of medication, not attending appointments, or failing to make lifestyle changes. Measuring non-adherence is essential in psychology and healthcare because it helps identify why patients might not stick to treatments and allows for interventions to improve health outcomes. Measures of non-adherence can be broadly categorised into subjective, objective, and biological approaches, each with its own ways of gathering data.

Subjective methods for measuring non-adherence

Subjective measures involve gathering information directly from patients about their adherence behaviours. These methods depend on self-disclosure, which can provide insights into personal experiences but may be influenced by biases.

Self-report questionnaires

Self-report involves patients filling out forms to describe their adherence to treatment. For example, the Medication Adherence Report Scale (MARS) is a questionnaire using a five-point rating scale to assess how well patients follow their medication plans.

Strengths of self-report questionnaires:

• Cost-effective and efficient - They are inexpensive to produce and quick to complete, allowing data collection from large groups.
• Produces quantitative data - Responses can be easily scored and analysed numerically, which supports statistical comparisons.
• High reach and generalisability - Questionnaires can be distributed widely, increasing the applicability of findings to broader populations.

Weaknesses of self-report questionnaires:

• Reliance on memory - Patients may forget details, leading to unreliable responses.
• Social desirability bias - Individuals might give answers they think are expected, reducing the validity of the data.

Semi-structured clinical interviews

A semi-structured clinical interview is a guided conversation between a patient and a healthcare professional, focusing on adherence to aid diagnosis and treatment. Tools like the Medical Adherence Measure (MAM) are used to draw out specific details about how patients follow their regimes. The success of this method often depends on building a trusting relationship, as outlined in research by Zelikovsky and Schast (2008), so patients feel safe being honest.

Strengths of semi-structured clinical interviews:

• Detailed qualitative data - They provide in-depth insights into patients' experiences and reasons for non-adherence.
• Enhanced validity and usefulness - The flexible format allows probing for more accurate information, making the data more applicable to real-world care.

Weaknesses of semi-structured clinical interviews:

• Time and cost intensive - Conducting interviews requires significant resources and practitioner time.
• High drop-out rates - Patients may not complete the process, limiting the sample size.
• Lower generalisability - Results from small, specific groups may not apply widely.

Objective methods for measuring non-adherence

Objective measures focus on observable evidence of adherence, such as tracking medication usage through physical means. These methods aim to reduce reliance on patient recall by using tangible records, making them more reliable in certain contexts.

Pill counting

Pill counting involves checking the number of pills remaining in a patient's supply, often done at clinics. To improve accuracy, unannounced checks via telephone or home visits can be used.

Strengths of pill counting:

• Reduces manipulation - Surprise checks prevent patients from altering counts, as supported by Kalichman et al. (2008), who found 92 per cent agreement between telephone/home counts and viral load measures in HIV-positive patients.
• Increases validity - Objective verification provides a more trustworthy assessment of adherence.

Weaknesses of pill counting:

• Patient burden - Requires patients to bring medication to appointments, which can be inconvenient.
• Potential for manipulation - If patients know when checks occur, they might discard pills to appear adherent, lowering validity.

Medication dispensers

Medication dispensers are devices that release pills at scheduled times, often with alarms to remind patients. They record when pills are removed, including dates, times, and frequency.

Strengths of medication dispensers:

• Patient benefits - Reminders increase the likelihood of taking medication, potentially reducing relapse rates.
• Reliable measurement - They provide consistent data on usage patterns.

Weaknesses of medication dispensers:

• Limited validity - Removal from the dispenser does not guarantee the pill was ingested.
• Addresses only forgetfulness - They do not help with intentional non-adherence.

Biological methods for measuring non-adherence

Biological measures confirm adherence by testing bodily samples for traces of medication. These provide direct evidence that drugs have been taken, allowing for personalised dosing adjustments.

Urine analysis

Urine analysis involves patients providing a sample in a sterile container, which is then tested for medication presence.

Strengths of urine analysis:

• Stability and convenience - Samples remain chemically stable for up to 14 days when refrigerated, and the process is non-invasive and inexpensive.
• Objective results - Visual indicators provide clear, unbiased evidence.

Weaknesses of urine analysis:

• Interference risks - Interactions between drugs or with food can affect accuracy.
• Limitations with multiple medications - Not suitable for patients on complex regimes, as it may not distinguish between substances.

Blood sampling

Blood sampling tests for medication levels in the blood. Traditional methods involve drawing blood, while dried blood spot (DBS) testing uses a small, dried sample.

Strengths of blood sampling:

• High reliability - Burnier (2020) showed DBS testing matches traditional plasma testing for detecting hypertension drugs.
• Less stressful options - DBS is easier and less invasive than full blood draws, making it suitable for more patients.

Weaknesses of blood sampling:

• Invasiveness - Traditional sampling can be unpleasant or stressful, limiting its use for some individuals.

Riekert and Drotar (1999)

This study examined how non-adherence in adolescents with diabetes relates to participation in research, highlighting implications for measuring adherence.

Method

• Involved 52 out of an original 94 families, including adolescents aged 11-18 who had diabetes for over a year.
• Recruited via a clinic, with comparisons to non-participants.
• Adolescents were interviewed using the Adherence and IDDM Questionnaire-R, covering diet, glucose testing, and preparedness for hypoglycaemia (low blood sugar).
• Blood glucose tests were monitored via a reflectance meter, and metabolic control was assessed at clinics.
• Parents completed demographic questionnaires, and families mailed back additional forms.
• Medical charts of all 94 adolescents were reviewed for glucose testing frequency, metabolic control, and demographics of non-consenters.

Results

• Demographics were similar across completers, non-returners (those not mailing questionnaires), and non-consenters.
• Adolescents from non-returner families tested blood glucose less often than those from completer or non-consenter families.
• Non-returner families showed lower overall adherence rates compared to completers.

Conclusions

Lower adherence is linked to reduced participation in adherence studies, suggesting that research may underestimate non-adherence by missing less adherent groups.

Evaluation

• Strengths - Provides real-world application by identifying organisational issues in non-participating families, aiding targeted interventions.
• Limitations - Ethical concerns arise from using non-consenters' data without permission, violating informed consent principles.

Chung and Naya (2000)

This research used electronic monitoring to evaluate adherence to oral asthma medication, demonstrating the effectiveness of objective measures.

Method

• 47 adults with asthma, aged 18-55.
• After a 2-3 week screening, participants underwent 12 weeks of treatment with one pill twice daily.
• Tablets were in bottles with TrackCap devices that recorded opening times without participants' knowledge (though informed consent was obtained for the study).
• Both tablet counts and TrackCap data were analysed.

Results

• TrackCap showed 80 per cent compliance (bottle opened twice daily), while tablet counts indicated 89 per cent, possibly due to removing multiple tablets at once.
• Exact compliance (two tablets 12 hours apart) was 64 per cent for both measures.
• 20 per cent under-complied by removing only one tablet daily, and 10 per cent had no compliance for up to eight days.

Conclusions

Devices like TrackCap effectively measure adherence, revealing patterns not captured by counts alone.

Evaluation

• Strengths - Objective quantitative data increases validity by avoiding biases like misremembering.
• Limitations - Participants knew adherence was being studied, potentially inflating rates; blinding to the monitoring method could improve validity.
• Ethical issues - Deception about the device raises concerns about fully informed consent.

Overall strengths and weaknesses of measuring non-adherence

Methods for measuring non-adherence offer valuable insights but come with trade-offs in practicality and accuracy.

Issues and debates in measuring non-adherence

Research on non-adherence intersects with broader psychological debates, particularly around data types and practical applications.

Quantitative and qualitative data

Quantitative data involves numerical measurements, like pill counts or electronic records, offering objective, comparable results. Qualitative data provides descriptive insights, such as from interviews, revealing reasons behind behaviours. Riekert and Drotar (1999) combined both through method triangulation (using multiple approaches) to enhance validity. In contrast, Chung and Naya (2000) focused on quantitative measures, which showed adherence levels but not underlying motivations, limiting depth.

Application to everyday life

Understanding non-adherence through these measures has direct real-world value. It improves healthcare professionals' knowledge of why patients might not follow advice, leading to better strategies like reminders or support systems.