In this paper, we have reported on one of the largest published surveys of patients with inflammatory bowel disease. The sample was drawn from the membership of the Crohn's and Colitis Foundation of Canada. The primary strengths of our sample are that it is (1) very large, (2) geographically diverse, (3) diverse in terms of patient and disease characteristics and (4) non-clinic based. However, it is not a true population-based sample, which would be most desirable for obtaining unbiased results. How representative our sample is of the general IBD population (freedom from bias) will be affected by who chooses to join the CCFC and who chose to complete the questionnaire. We would have expected from our pilot study that 16% of respondents would have indicated that they did not have IBD. However, only 9% of questionnaires were returned with this indicated. This suggests that those who did not have IBD were less likely to respond to the questionnaire than those with IBD.
In our study we did not validate the respondents' diagnosis of IBD. We did exclude anyone who did not classify themselves into one of our three categories of IBD (We also excluded anyone who wrote in another form of colitis, such as collagenous colitis). A study of Crohn's and Colitis Foundation of America members in North Carolina found that 98% of members who self-reported IBD were judged to have definite or probable disease based on clinical assessment of x-ray, endoscopy or pathology reports.[10
] Examining the drug and health care experiences provides some further validation of our sample. Only 637 (23%) had not used at least one IBD drug therapy in the past 12 months (excluding antidiarrheals, antibiotics and narcotics). Of these, only 199 (7% of total sample) had not undergone at least one surgery for their IBD. Finally, 94 of the 199 (3% of total sample) had never been hospitalized because of their disease. Therefore, we are confident that our sample is not significantly contaminated by people who do not have IBD. We have also previously found that there was a high degree of agreement between patient self-classification as to disease type and that recorded in their medical charts.[9
To better understand how our sample relates to both the larger IBD population and to clinic-based samples, we compared demographic and disease characteristics of this sample to two other published samples.
First, we have previously published on the CAM use of a gastroenterology-clinic based IBD sample.[4
] In comparison to that sample, our current sample is slightly older (mean age 46 vs. 40 years), contains fewer females (61% vs. 68%) and is better educated (73% vs. 64% with education beyond high-school degree). However, as expected, the current sample also contains more people with less severe Crohn's disease as shown by lower rate of hospitalizations (83% vs. 92%) and surgery (65% vs. 79%) and, although measured in different ways in the two studies, probably less use of oral and iv corticosteroids. In contrast, the ulcerative colitis sample includes a larger proportion of patients who have undergone surgery (presumably proctocolectomy 16% vs. 6%).
The second comparison is the population-based sample from the University of Manitoba IBD Database.[11
] Our current sample is also older than this population and is especially underrepresented by patients in the 20 – 29 year old age group. Our sample also has a larger proportion of females and a higher education level than the Manitoba sample, although employment levels appear roughly similar. The higher socioeconomic status of our sample could reflect that this group is more interested in membership and/or could also be the result of the very modest annual membership fee limiting access to those of lesser means. Finally, the Manitoba sample classified patients as Crohn's disease or ulcerative colitis only, with a ratio of 1.17 Crohn's disease patients to ulcerative colitis patients. In our sample, we had nearly twice the number of people identifying themselves as having Crohn's disease versus ulcerative colitis.
Therefore, there are important differences between our sample and two other IBD populations. First, as desired, our current sample does appear to include a broader range of patients, especially in terms of patients with less severe disease or UC patients who have previously undergone surgery, than our clinic-based sample. However, in contrast to a population-based sample, our current sample is older, contains a greater proportion of females and those with Crohn's disease, and is better educated. These differences probably are the result of self-selection into the CCFC membership rather than due to who chose to respond to our questionnaire. The proportion of non-respondents who had a female title (i.e. Mrs. Ms.) in the CCFC mailing list was similar to the proportion of females in our analysis sample.
Based on these comparisons, we believe that this sample achieved our goal of obtaining a large, geographically diverse sample, which although not necessarily fully representative of the general IBD population, is likely more so than more readily available clinic samples. Creating a national sample for a mailed survey using the methodology of the Manitoba IBD cohort clearly would have been a daunting, if not impossible, task. Biased prevalence estimates of parameters of interest could be derived from our sample if they were associated with sex, age or educational achievement. However, these limitations can be acknowledged and potentially minimized through stratified analysis or standardization.
One aspect of quality of medical care is access to appropriate treatments. Most previous studies of physician practice patterns in IBD have been of members of specialty societies or IBD organizations and have relied on physician self-report.[14
In general we could find no evidence of significant variations in medical treatments due to gender, region of residence or income level. We did see differences associated with age. In general older patients were less likely to have received common IBD medical treatments in the preceding 12 months although they reported similar levels of disease activity.
Immunosuppressive drugs, predominantly the purine analogs, have become increasingly emphasized in the treatment of Crohn's disease as a way to reduce corticosteroid exposure, maintain remission and alter the natural history of the disease.[17
] We found that 24% of Crohn's disease patients reported the use of azathioprine or 6-mercaptopurine in the previous 12 months. There is limited data on immunosuppressive use in IBD populations. Feagan et al. reported that 5% of patients with a Crohn's-related medical claim in several United States employee health plans had used 6 MP/Aza over a 1-year period from 1994–1995.[18
] Metge et al. reported that 9% of the patients in the University of Manitoba IBD database who received at least one pharmaceutical prescription in 1997 filled a prescription for an immunosuppressive agent.[12
] Although the populations and measures of 6 MP/Aza use differ between the studies, our data combined with these published studies does support a growing use of immunosuppressive drugs in Crohn's disease. Consistent with the generally accepted indications for immunosuppressive use, we found greater 6 MP/Azathioprine use by those who had used intravenous or oral corticosteroids in the past 12 months, those with multiple hospitalizations in the past five years and those who had undergone surgery within the past two years. Metge et al. reported that men were more likely to receive immunosuppressives than women.[12
] However, we found no difference, even when examining the age groups that would include women of child-bearing age.
Infliximab entered clinical trials in Canada in mid-1999. A compassionate release program was instituted in the fourth quarter of 1999 and ran until the drug was given approval by the Health Protection Branch in June 2001. Despite this survey being conducted only in late 2001, nearly 6% of Crohn's disease patients reported having used infliximab. We cannot tell what proportion of these received the drug initially as part of a clinical trial. Patients with markers of more severe disease (hospitalizations, surgery, steroid use) were those most likely to have received infliximab. Although a survey is clearly not the appropriate way to measure the effectiveness of an agent, it is interesting to note that only 20% of those who had received infliximab rated the current activity of their disease as inactive or mild and 43% rated it as at least quite active.
We did find regional variations in prior surgery among UC patients. It is not possible to exclude selection bias. This could occur if the probability of remaining a member of the CCFC after undergoing surgery depended on place of residence. This is unlikely. It is also possible, though seemingly unlikely, that regional variations in surgery could be due to regional variations in post-surgical UC patients responding to our questionnaire. We did initially have difficulty in having some patients with prior proctocolectomy respond to our questionnaire because they considered themselves to no longer have IBD. We received many phone calls after the first questionnaire was mailed out. We contacted each caller to indicate that they should complete the questionnaire and when we mailed the second questionnaire to non-responders we specifically indicated that those UC patients who had previous surgery should still complete the questionnaire. In the absence of these two unlikely scenarios, how can one explain the differences in the proportion of patients who underwent surgery in different areas of the country? One explanation could be regional variations in the use of cyclosporine for acute severe disease and azathioprine for chronically active disease. However, we could find no evidence of regional variation in 6 MP/Aza use among UC patients that had not undergone prior surgery. The number of patients reporting IV cyclosporine use in the past 12 months (5) precluded any meaningful analysis. Regional availability of colorectal surgeons could also affect surgical rates, but this could not be answered with our data.
In conclusion, we have conducted a national survey of IBD patients. Our sample includes a broader range of patients that those typical of clinic samples, especially in terms of patients with less severe disease and UC patients who have undergone surgery. We have found variations in the treatment of inflammatory bowel disease in Canada. Reassuringly, we have not been able to demonstrate significant variations in medical treatment based on place of residence, gender or income levels. Unexplained variations based on age were seen and should be evaluated further in future studies.