INTRODUCTION
The terms adherence, compliance, and concordance relate to different aspects of the health care professional / prescriber – patient relationship (Box 1) [1]. The focus of this article is on non-adherence with rescue medication amongst patients with breakthrough cancer pain.

Box 1 – Concepts of adherence, compliance and concordance [1].

It is estimated that between 33-50% of medicines prescribed for long term conditions are not taken as recommended [2]. A number of factors have been associated with non adherence, including patient characteristics, the nature of the illness, the type of treatment, and the health professional – patient relationship [3]. The reasons are often multiple and complex.

Non-adherence may be:

• Unintentional - the patient wants to follow the treatment recommendations, but has practical problems in doing so.
• Intentional - the patient decides not to follow the treatment recommendations.

Non-adherence with analgesics is associated with worse pain control, and so worse quality of life. Furthermore, non-adherence leads to wastage of resources, and may lead to compromise of the healthcare professional – patient relationship.

STUDIES OF ADHERENCE / NON-ADHERENCE
A number of studies have reported issues of non-adherence with rescue medication amongst patients with breakthrough cancer pain [4-7].

Adherence with “around the clock” and “as needed” medication was investigated in a longitudinal study of 65 oncology patients in seven outpatient settings in the United States of America [4]. Adherence rates for around the clock medication ranged from 84.5-90.8%, whilst adherence rates for as needed medication ranged from 22.2-26.6%. The reasons for the greater non-adherence with as needed as compared with around the clock medication were not reported in this study.

Ferrell et al reported a discrepancy between the rescue medication prescribed by healthcare professionals and the actual rescue medication utilised by oncology patients in the home care setting [5]. Specifically, 96% of patients were taking too low a dose, 3% of patients were taking the prescribed dose, and 1% of patients were taking too high a dose. Indeed, the mean dose taken was only 21% of the dose prescribed. The reasons for the non-adherence were not reported in this study.

The reasons underlying the use / non-use of rescue medication were explored in a study of 120 patients attending an oncology centre in the United Kingdom [6]. Eighty seven (73%) patients had breakthrough pain, and 81 had been prescribed rescue medication. Of these 81 patients, 3 had never taken the rescue medication, 15 used the rescue medication every time they experienced breakthrough pain, and 63 patients used the rescue medication only some of the time they experienced breakthrough pain. The reasons for non-adherence are shown in Table 1.

The observation that patients do not take rescue medication every time they experience breakthrough pain was confirmed in a study of 50 patients admitted to a hospice in the United Kingdom [7]. On average, patients used rescue medication for only two-thirds of episodes prior to admission. The reasons for not taking rescue medication included lack of efficacy (n = 21), adverse effects (n = 19), concerns about overdosing (n = 10), concerns about effect on daily routine (n = 8), and lack of instructions (n = 4).

STRATEGIES FOR IMPROVING ADHERENCE
It should be acknowledged that non-adherence with rescue medication is not always a negative phenomenon. For example, patients often appropriately “down-titrate” the dose of rescue medication in order to improve the tolerability of the rescue medication. (The utility of rescue medication depends on the balance between efficacy and tolerability). It is important to assess all patients for adherence with rescue medication, and (when relevant) to determine the reasons for non-adherence with rescue medication.

A number of strategies may be helpful in increasing adherence to rescue medication, including improved communication with patients (provision of information), increased patient involvement in decision making (understanding patient’s perspective), adequate follow up of patients (e.g. review of medication), and improved communication between healthcare professionals. Unintentional non-adherence may be resolved by improving the tolerability of the rescue medication (e.g. managing adverse effects), or the ease of use of the rescue medication (e.g. changing formulation / preparation).

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Table 1 – Patients’ reasons for not always taking breakthrough medication [6].

References

[1]. Horne R. Compliance, adherence and concordance. Chest 2006; 130: 65S-72S.
[2]. National Institute for Health and Clinical Excellence. Medicines Adherence: Involving Patients in Decisions About Prescribed Medicines and Supporting Adherence. NICE: London; 2009.
[3]. Griffith S. A review of the factors associated with patient compliance and the taking of prescribed medicines. British Journal of General Practice 1990; 40: 114-6.
[4]. Miaskowski C, Dodd MJ, West C, Paul SM, Tripathy D, Koo P et al. Lack of adherence with the analgesic regimen: a significant barrier to effective cancer pain management. Journal of Clinical Oncology 2001; 19: 4275-79.
[5]. Ferrell BR, Juarez G, Borneman T. Use of routine and breakthrough analgesia in home care. Oncology Nursing Forum 1999; 26: 1655-61.
[6]. Davies AN, Vriens J, Kennett A, McTaggart M. An observational study of oncology patients’ utilization of breakthrough pain medication. Journal of Pain and Symptom Management 2008; 35: 406-11.
[7]. Zeppetella G. Opioids for cancer breakthrough pain: a pilot study reporting patient assessment of time to meaningful pain relief. Journal of Pain and Symptom Management 2008; 35: 563-7.

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