Measuring Adherence and non-adherence

Subjective – Self-reports

RIEKART AND DROTER (1999) developed a technique used to ask questions related to how much patients are adhering to their treatment. It is good for detecting those, who admit to adherence difficulties, but will miss-classify abut 50% of patients, who deny problems or are unaware.

Strengths:

• High Validity – it is asking patients directly about their compliance.
• Way to gather data quickly and cheaply.
• Kaplan & Simon (1990)  – noted that if the questions are direct and simple to answer, this techniques can be used successfully to measure rates of adherence.

Weaknesses:

• Social desirability bias – patients may answer questions in a certain way to appear more socially desirable, which may alter the results and make them less reliable.
• Fixed choices on questions leave little space for explanation from the patient, which make it less valid.

Objective

CHUN AND NAYA (2000) developed a medication dispenser called Tracap, which recorded the date and time a pill left the the bottle. 59 patients took part in the study and were told what the device did but were not told that the research was being conducted. It was found that the adherence rate over 12 weeks was of 71%. 

Strengths:

• Reliable – the method has been consistent over time and produces high rates of adherence.
• Good way of measuring without demand characteristics or social desirability affecting the results.

Weaknesses:

• Low validity – the researchers cannot be sure that the medicine was taken even if it left the bottle. 
• Ethical problems – participants did not give full informed consent since they did not know they were being studied.

ROTH (1978) developed blood and urine tests to detect the levels of the drug that the patient should have consumed. It is considered one of the best measure for adherence and intake of drugs/substances.

Strengths:

• Reliable –  the method is scientific based, therefore it can replicated easily and the same results will be found. Also, demand characteristics or social desirability bias cannot affect the findings.
• Scientific – the results cannot be affected by the subjectivity of doctors as they provide quantitative data, which does not need to be analysed. This makes the results more valid.

Weaknesses:

• Expensive – compared to other methods available, biochemical tests are quite costly because they involve elaborate scientific material. 
• The tests do not show total adherence to a regime because it only suggests that enough drug has been ingested to be detectable. Therefore, there is no guarantee if the patient took the right dose and respected the regime.

SHERMAN ET AL (2000) developed repeat prescriptions for patients who are on longer-term treatment and have the option to ask for their medicines repeatedly without having to see a doctor and asking for a prescription. The belief is that patients have the motivation to pick up their medicines, then they must be adhering to the regime. However, carers may pick up the drugs and these may not be consumed by the patient.