Adherence and Utilisation
Adherence to nebulised antibiotics in cystic fibrosis

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Abstract

Objective

To examine the adherence of patients with cystic fibrosis to nebulised antibiotics.

Methods

A longitudinal design with adherence data collected over 12 weeks. 38 patients (mean age 24.6 years, S.D. 5.3) were recruited from an adult cystic fibrosis (CF) clinic. Adherence was electronically monitored using a Prodose adaptive aerosol delivery (AAD) device.

Results

Three indices of adherence were calculated: mean percentage of times the nebuliser was used as prescribed was 50.0% (S.D. = 39.7, range 1.1, 155.6); mean percentage of days fully adhered was 31.6% (S.D. = 29.4, range 0, 97.2); mean percentage of days nebuliser used at least once was 57.1% (S.D. = 34.2, range 3.3, 100).

Conclusion

Rates of adherence were generally low. Adherence was not associated with any variables apart from age. There were wide variations between individuals, and differences in rates of adherence depending on how this was defined, with potentially important health consequences for the patients.

Practice implications

Technology that improves medication administration may still be associated with low rates of adherence. Health professionals need to be mindful of the pattern of non-adherence for each individual, and factors which may be influencing this.

Introduction

Cystic fibrosis (CF) is a life-threatening hereditary multi-system disease predominantly affecting the pancreas and lungs. Advances in treatment have led to significant improvements in prognosis though this depends crucially upon adherence to treatment.

Non-adherence is a major problem in chronic illness, with rates of adherence noted between 30% and 70% [1]. Unsurprisingly, the demands of the complex treatment regimen in CF are associated with poor adherence [2].

One major confound in this literature is that definitions of non-adherence and the method of measurement often differ between investigators [3]. Self-report is often unreliable [4], as are methods such as counting pills [5]. Biochemical methods such as testing urine are more objective, but have been criticised for potential inaccuracies [5].

In CF, the treatment regimen has several components. Adherence is high to oral and intravenous medication (80–95%) [2], but low to nebulised therapies such as prophylactic antibiotics (65–80%) [6].

A major advance in measuring adherence to nebuliser use has been memory microchips concealed in the device. Research using these chips shows average adherence to nebulisers in CF ranges from 57% over the long-term [7] to 86% during a 7-day trial [8]. One complicating issue, however, is the ability of the patient to use the device effectively. Adaptive aerosol delivery (AAD) systems, such as the Prodose™ are breath activated and programmed to deliver a pre-set dose of medication, giving feedback to the patient and signalling audibly when that dose is complete [9], [10]. Significantly more complete doses are taken with the AAD system when compared to conventional nebulisers [11]. It is also easier to use: nebulisation time for AAD devices is reported to be significantly less than for conventional nebulisers [12] and patients using the device have reported that they found it better to use than their previous nebuliser [13].

These new devices therefore offer the possibility that some of the practical barriers to achieve good adherence such as time needed and ease of use may be reduced. The devices still require the patient to initiate treatment, and therefore afford the opportunity for accurate measurement of adherence.

This study aimed to assess the adherence of CF patients to nebulised antibiotics utilising an accurate, objective method.

Section snippets

Participants

Participants were all over 18 years of age with a diagnosis of CF. 101 adult patients attending a regional CF clinic were prescribed aerosolised colistin. Fifty-four (53.4%) were ineligible for various reasons: participation in another trial (n = 15); undergoing post-transplant or eradication therapy (n = 14); unable to be contacted (n = 13); too ill (n = 7); trying to conceive or pregnant (n = 3); substance user (n = 1), in prison (n = 1). Forty-seven patients were invited to participate. Six declined and

Results

The mean age of participants was 24.6 years (S.D. 5.3). Twenty (52.6%) of the sample were male. Most were single (n = 22, 61.1%), fifteen (39.4%) were married or co-habiting and one divorced. Eighteen participants (47.4%) were in full or part-time employment, fifteen (39.5%) unemployed or receiving invalidity support and five (13.1%) were students. Participants were white European (n = 34, 89.56%) or of Asian (India/Pakistan) origin (n = 4, 10.5%). Patients had been using a nebuliser for a mean number

Discussion

There are two important findings in this study. First, that there was great individual variation in rates of adherence in this sample of CF patients, with adherence generally being low. On average, participants used their nebuliser approximately half of the prescribed times. This is similar to the findings of Laurans et al. [16] who found patients were using their expectorants 53% of the times prescribed.

The second finding is that different definitions of adherence produced different results.

Acknowledgements

The authors would like to thank Richard Marsden and Alex Black at Profile Therapeutics (Respironics) for their support of this study, and for the provision of the Prodose nebulisers.

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