The survey used an internet-based questionnaire and was conducted during the period from April 2011 to June 2011. Based on knowledge from a large Danish research project that took place from 2004 to 2010 within the Danish Multiple Sclerosis Society and investigated treatment collaboration between conventional and complementary practitioners [27
], a questionnaire was developed, tested, and validated using cognitive interviews as well as assessments by an expert group of Nordic neurologists [34
]. The questionnaire was developed in Danish and translated into the Nordic languages, then back to Danish by health professionals with Danish or the other Nordic languages as native language/second language, respectively. A synthesis of the original and the retranslated Danish versions was produced for each Nordic language, and the questionnaires were adjusted. The questionnaire was programmed in IBM Inquisite ASP, using skip sections and branching and thereby ensuring ease of response for a variety of respondents.
As previous Nordic studies had shown a lack of consensus regarding the definition of CAM [35
], a questionnaire was developed to collect information about both the use of conventional as well as CAM treatments. The terms conventional or CAM treatment were not used in the questionnaire, to avoid response bias related to these labels. This strategy also provided the possibility of investigating the use of conventional and CAM treatments in combination. For each treatment, participants were asked whether they used it and what their motives for use were. Use of disease-modifying medicine for MS was not included in the study.
Based on power calculations and expected dropout due to members who were deceased, lived abroad, or did not have MS (registration error), 1050 people with MS were selected randomly from the member registers of the Swedish, Norwegian, and Finnish MS societies, and 3500 people with MS were selected randomly from the member register of the Danish MS society. In Iceland, the sample included the total number of all individuals who appeared in the member register of the national MS society (In Iceland, it has not been possible to distinguish between members with MS and supporting members in the register. Letters were therefore sent to all members of the Icelandic MS society (n = 780), asking only people with MS to answer the questionnaire.).
A letter with a personal code was sent to all respondents, asking them to fill out the questionnaire online. Receiving the questionnaire in paper form was not an option. Reminders to nonrespondents were sent twice. As shown in , the response rates varied from 50.9 to 61.5.
Representative characteristics of the study population.
In Iceland, it was not possible to distinguish between MS Society members with MS and supporting members. Therefore, an analysis of representativeness could not be carried out. Keeping this in mind, the results of the Icelandic data are still presented in the subsequent sections.
Comparative analyses included use of specific CAM modalities as well as specific symptoms/health issues addressed by CAM users as rationale for use. As none of the five countries constitute a natural a priory reference, we have found it most correct to employ a changing reference. The country with the lowest prevalence of a specific variable was hence used as reference for presenting odds ratios (ORs), indicating the comparative relations for each variable. P values have not been included in the tables due to risk of visual complexity, but statistical significance has been determined by interpretation of 95% confidence intervals (CIs) and is marked by “+” in the tables. As the choice of performing multiple comparisons entails the risk of mass significance and thereby finding statistical significance that are due to random error rather than real differences, we have been highly aware of interpreting significant differences in single variables in an overall perspective.
The definition of CAM treatments was based on the National Center for Complementary and Alternative Medicine's (NCCAM) definition of CAM as “a group of diverse medical and health care systems, practices, and products that are not generally considered part of conventional medicine” [38
]. The specific CAM treatment modalities used in the questionnaire were chosen on the basis of known prevalence of use in the Nordic countries, and room was left open for addition of nonpredefined modalities by respondents.