Patients are often lying when they say they have regularly taken the prescribed medicine . Hippocrates, 400 bc
The issue that Hippocrates was highlighting was that of compliance – an important field of medicine that has been the subject of medical research since the beginning of the 20th century. In the contact lens field, studies of compliance commenced only in the mid-1980s, with the first peer-reviewed journal article on this topic being published by .
Although patients sometimes unwittingly, carelessly or even recklessly contribute to their own misfortune ( Fig. 39.1 ), the model offered by Hippocrates is perhaps a little too simplistic. defined compliance as ‘the extent to which a patient’s behaviour coincides with the clinical prescription’. This is a more instructive definition in that it highlights the critical importance of the practitioner–patient relationship in avoiding adverse events. This chapter will review the field of compliance as it relates to contact lens wear and will conclude with the presentation of a contact lens-specific compliance model.
Consequences of Noncompliance
Although full compliance with practitioner instructions does not guarantee trouble-free lens wear ( ), it is worth considering the possible consequences of noncompliance because the conclusions from such an analysis provide the rationale for studying this topic. In general, noncompliance will result in the following adverse effects: reduction of treatment efficacy, secondary problems, incorrect prescribing, wasting of practitioner chair time and wasting of patient time. Clearly, healthcare delivery will be enhanced if adverse consequences of noncompliance can be minimized or eliminated.
Extent and Pattern of Noncompliance
It is not always possible to characterize a person simply as compliant or noncompliant because there will be variations in the pattern of noncompliance over time, and changes in the extent of noncompliance at a given instance in time. Because of this, noncompliant behaviour in some people may continue undetected for some time. There is a greater likelihood of detecting consistent and/or total noncompliant behaviours at an aftercare visit.
Duration of the Prescription
In the general healthcare field, the extent of noncompliance has been found to be related to the duration of the prescription. For short-term medication (e.g. a 9-day course of antibiotics) about 20%–30% of patients will be noncompliant. Higher rates of noncompliance are found for long-term regimens: 30%–40% of patients are noncompliant with preventive or prophylactic measures (e.g. using sun protection creams outdoors in patients susceptible to skin cancer) and more than 50% of patients do not adhere to advice relating to long-term therapy (e.g. ongoing medication for chronic hypertension) ( ).
The prescription of contact lenses and contact lens care systems is akin to a long-term preventive measure; it is therefore not surprising that in 2011 an international survey of 4021 lens wearers found that full compliance with all aspects of the lens care regimen was very rare for most lens users, although better (15% of wearers) for daily disposable lenses ( ). had noted similar levels of contact lens noncompliance 17 years earlier, indicating that little has changed in this regard in the intervening period. Levels of noncompliance with respect to contact lens care are broadly consistent with estimates of patient noncompliance reported in general medicine ( ).
Erroneous Contact Lens Procedures
A number of epidemiological studies have identified risk factors that are associated with an increasing likelihood of microbial keratitis during contact lens wear ( ). Many of these are ‘nonmodifiable’ and include age, gender and socioeconomic status. Others are ‘modifiable’; in turn, these can be subdivided into factors that are or are not related to ‘compliance’. identified eight modifiable, patient compliance-related behaviours that put the patient at increased risk for microbial keratitis:
nonprescribed overnight wear
excessive duration of extended wear
excessive lens replacement interval
inadequate case cleaning
failure to use correct disinfecting solution
failure to rub and rinse lenses
topping up solution
identified that showering while wearing lenses was the greatest personal hygiene risk factor for contact lens-related microbial keratitis, with an odds ratio of 3:1. This risk increased to 7:1 if patients showered daily in lenses. The odds ratio for sleeping in lenses was 3:1, and the most at-risk age group was 25–54.
Surveys conducted in 14 countries identified the proportion of correctly behaving wearers for modifiable patient compliance-related behaviours (MPCRBs) for daily disposable lenses ( Fig. 39.2 ) and daily-wear reusable lenses ( Fig. 39.3 ) ( ). Statistical analysis revealed that, overall, country was a significant independent factor in predicting the total number of noncompliant steps. The key difference here was the greater number of noncompliant MPCRBs reported by South Korean respondents, with a largest least mean square value of 3.97 compared with the other countries, which ranged from 2.93 in France to 3.45 in Japan.
The number of noncompliant steps also differed across the lens types. Daily disposable lenses were associated with the least noncompliance, followed by reusable extended-wear soft lenses and the remaining lens groups (reusable daily-wear soft planned replacement lenses, nonplanned replacement soft lenses and rigid lenses) performing similarly. Daily replacement wearers were found by to be most likely to be compliant with contact lens replacement, but all subjects in their study, including wearers of both reusable and daily disposable lenses, had similar overnight wear noncompliance.
Gender was predictive of the number of noncompliant MPCRBs, with better compliance for women (3.12) than for men (3.28). Age was also demonstrated to be an important factor, with the number of noncompliant steps diminishing with the age of the respondent. The rate of improvement with age was about 0.15 noncompliant MPCRBs per decade of life.
Respondents using their lenses more frequently tended to be less compliant than did those using lenses on a part-time basis. Subjects using lenses on a full-time basis typically performed 3.47 noncompliant MPCRBs compared with 2.41 noncompliant steps for those using lenses for a single day per week. Respondents were more compliant if they had consulted with an eye-care practitioner more recently ( ).
Reasons for Noncompliance
surveyed 805 patients wearing daily disposable contact lenses in four countries – Australia, Norway, the United Kingdom and the United States – to determine the rate of noncompliant behaviour and the reasons for this. Although daily disposable lenses are designed to be worn once only and discarded after each use, overall 9% of patients were noncompliant, with the specific rates of noncompliance in the four countries being: Australia 18%, the United States 12%, the United Kingdom 7% and Norway 4%.
The reasons patients gave for reuse of lenses is shown in Fig. 39.4 . Among those who did reuse their daily disposable lenses, various methods were used to store lenses overnight ( Fig. 39.5 ) and a number of different of solutions employed for this purpose ( Fig. 39.6 ). Patient perceptions of the main risk involved in reusing daily disposable lenses are shown in Fig. 39.7 ( ). Similar reasons for noncompliant behaviour in the United States have been reported for reusable lenses ( ), with one key difference: the main reason cited for wearing reusable lenses longer than recommended was forgetfulness – either forgetting which day to replace lenses or forgetting to reorder lenses.
Compliance With the Incorrect Prescription
The vast majority of practitioners endeavour to dispense the correct and proper prescription; it would be unethical to do otherwise. However, in the past there have been well-documented contact lens-related cases of practitioners dispensing the incorrect prescription based on misinformation or a misinterpretation ( ). An example of this was the recommendation by 6% and 4% of practitioners in Canada and the United States, respectively, that patients reuse their daily disposable lenses ( ).
Whether inadvertent or deliberate, incorrect prescribing is a reality that must be considered in order to provide a comprehensive analysis of noncompliance. Fig. 39.8 is a flow diagram that reveals five possible outcomes based upon the assumption that an incorrect prescription (or incorrect advice) has been dispensed to the patient. A tick indicates the likelihood of a positive outcome, and a cross indicates the likelihood of a negative outcome.