A. Definitions of adherence

The therapeutic management of systemic lupus erythematosus (SLE) is based on the type and severity of organ involvement and includes non-steroidal anti-inflammatory drugs, corticosteroids, hydroxychloroquine (HCQ) and immunosuppressive agents. The recent availability of new biological treatments, especially monoclonal antibodies, will modify this classic therapeutic approach. These new biologics are mostly targeted at patients with active disease . However, one of the main causes of persistent SLE activity despite treatment may be the lack of adherence to the treatment since “drugs don’t work in patients who don’t take them.” To avoid unnecessary treatment escalation, physicians should recognise non-adherent patients as accurately as possible, even if we acknowledge that this task is quite challenging. In this review, we first define adherence, and then we successively analyse the literature regarding the tools to assess non-adherence, the adherence rate in the general population and, specifically in SLE patients, the consequences of non-adherence, its determinants (also referred to as the barriers to adherence) and the actions that can be implemented to (try to) improve adherence.

Adherence or compliance, terms that differ mainly with regard to the patient’s active involvement (or lack thereof), is defined as “the extent to which a person’s behaviour (taking medication, following a diet programme, or modifying her/his lifestyle), corresponds with agreed recommendations from a health care provider.” . The term ‘adherence’ is preferred by many health-care providers. Indeed, ‘compliance’ suggests that the patient is passively following the doctor’s advice and that the treatment plan is not based on a therapeutic alliance or contract established between the patient and her/his physician. The notion of persistence refers to the ability of the patient to continue to take her/his treatment for the duration of the prescription.

The rate of adherence is usually reported as the percentage of the prescribed doses of the medication actually taken by the patient over a specified period of time. No consensual standard defines the adequate adherence. Most of the studies consider that rates >80% are acceptable, but in some conditions (e.g., infection with the human immunodeficiency virus), rates >95% may be required. By contrast, rates <20% are generally used to define non-adherence. However, it is not always possible to distinguish between non-adherent and adherent patients since there is a continuum from 0 to >100% (a few patients may take more than the prescribed amount of a drug).

The behaviour of non-adherent patients may vary widely. Consequently, non-adherence can be total or partial, continuous or intermittent, intentional or unintentional and recognised by the patient or not.