Ulcerative colitis (UC) is a ubiquitous disease, with a worldwide incidence rate varying from 0.5 to 24.5/100,000 persons per year [1, 2]. The highest incidence rates mainly occur in the most developed regions, notably North America and Western Europe. In Canada, the prevalence and incidence of UC are estimated as 267 cases per 100,000 and 12.9 cases per 100,000, respectively . In the United States, UC prevalence and incidence rates are estimated as 214 per 100,000 and 8.8 cases per 100,000 . From an European perspective, in 2000, the United Kingdom had a UC prevalence and incidence rate of 153 cases per 100,000 and 19 cases per 100,000, respectively .
Substantial costs are associated with the management of the disease. According to Cohen et al., the 2008 overall cost of UC in the European Union varied between €12.5–29.1 billion, which comprised medical costs (€5.4–12.6 billion) and absenteeism associated costs (€7.1–16.5 billion) . Consistent with these figures, the economic burden associated with UC in the United States was estimated at $US 8.1–14.9 billion in 2008. Health care costs represented $US 3.4–8.6 billion while productivity losses were $US 4.7–6.3 billion .
Still incompletely understood, UC is an inflammatory bowel disease that results from an excessive immune response leading to intestinal inflammation [1, 7]. The course of UC over time may consist of a repeated state of symptom exacerbation punctuated with periods of remission . The symptomatic relapse can be associated with constant diarrhea, rectal bleeding, abdominal pain, weight loss, and fatigue . A Westernized environment and lifestyle are linked to the appearance of inflammatory bowel disease, which may be associated with smoking, diets high in fat and sugar, medication use, stress, geographic localization and high socioeconomic status . However, their role remains uncertain and unconfirmed [1, 7, 11]. The only known risk factor associated with UC is heredity [8, 12]. Other factors, such as smoking status, have been associated with UC [8, 11].
The American College of Gastroenterology Clinical Practice Guidelines classify UC into 4 disease severities: (1) mild disease, (2) moderate disease (>4 stools/day, minimal signs of toxicity), (3) severe disease (>6 stools/day, fever, tachycardia, anemia, elevated erythrocyte sedimentation rate), and (4) fulminant disease (>10 stools/day, continuous bleeding, toxicity, abdominal tenderness and distension, transfusion requirement, colonic dilation) . Since there is no curative treatment for UC, this inflammatory disorder is generally controlled with pharmacological agents that are either used to control the symptoms and/or to attenuate the inflammation. Currently, the anti-inflammatory first line therapies for mild to moderate UC, include olsalazine and 5-aminosalicylic acid (5-ASA) also known as mesalamine . In Canada, the most commonly used treatments of the active principle 5-ASA are commercialized under 4 different names: Mezavant®, Asacol® and generics, Salofalk®, and Pentasa® . Compared to the other 5-ASA treatments, which need to be taken as 2 to 4 times per day, Mezavant® was designed to allow delayed and gradual release of 5-ASA in the colon due to its Multi Matrix® (MMX®) hydrophilic and lipophilic coating, thus it can be taken only once daily and was shown in clinical trails to be as effective as twice daily mesalamine formulations [16, 17].
In all chronic diseases, treatment adherence and persistence remain significant concerns, as these conditions may require medications to be taken for the entire or a major part of the lifespan. Consequences of non-adherence and persistence can be many including relapsing or worsening of disease, increased morbidity, or even mortality. Indeed, Kane suggested that the major consequences of non-adherence to 5-ASA for patients with UC are a five-fold higher risk of relapse, an increased risk of colorectal cancer and a reduced quality of life . Identification of risk factors associated with non-adherence in UC may improve patient management and consequently reduce relapse episodes, by providing more effective interventions intended for improving adherence. Importantly, the lack of adherence to UC treatments has been associated with a significant increase of costs, as non-adherent patients who are at an increased risk of relapse are likely to contribute to the overall high costs associated with the treatment of UC .
Although high non-adherence to medication has been reported in mild to moderate UC, little is known about adherence to the different 5-ASA treatments and determinants that can predict adherence and persistence. Therefore, the objectives of the present study were to estimate adherence and persistence to 5-ASA treatments and to identify the potential determinants of adherence and persistence in a real-life setting.