Recruitment
Participants of the study were recruited by the two largest German FMS-self help organisations and nine clinical institutions. The specialties of the clinical institutions were pain medicine and psychotherapy (N = 3), rheumatology (N = 2), complementary and alternative medicine (N = 2), physical therapy (N = 1) and pain therapy (N = 1). The settings were outpatient (N = 6), inpatient (N = 2) and day clinic (N = 1). The levels of care were secondary (N = 6) and tertiary care (N = 2) and rehabilitation (N = 1).
Inclusion- and exclusion criteria
Members of the self-help organisations had to report that the diagnosis of FMS had been established by a physician. Because there is no gold standard for the clinical diagnosis of FMS [15], the physicians of the participating study centers were free in their choice of FMS-diagnostic criteria. Patients who were not able to read German and patients with a FMS-diagnosis of <1 month’s duration were excluded. There were no other exclusion criteria.
Procedure
Clinical institutions
From November 1, 2010 to April 30, 2011 all consecutive patients with an established diagnosis of FMS at the participating study centres were asked by the physicians of these centres to take part in the study. The questionnaires were handed out by the physicians of the centres with a standardized letter explaining the focus of the study. The questionnaires were returned by the patients in a closed and anonymous envelope and kept away from the charts. At the end of the study the questionnaires were sent to the coordinating study centre.
Self-help organisations
The package of questionnaires was sent by the central office of the German League for people with Arthritis and Rheumatism to their regional offices with the request that the leaders of the local self-help groups distribute the questionnaires to their members during group meetings. The German Fibromyalgia Association included the package in the 4/2010 issue of its member journal „Optimist,“which was sent out by post to all members. Patients returned the questionnaires by post at their own cost to the central office. In addition, the questionnaires were available on the homepages of both self-help organisations. After downloading and completing the completed questionnaires, they were sent by mail, fax or email to the central offices. Employees of both central offices removed personal identifying information and sent the questionnaires to the coordinating study centre.
The participants (investigators and patients) of the study did not receive any reimbursement or compensation for participation.
Survey questionnaires
Demographic data and medical data were assessed by a questionnaire used in a previous multicenter German FMS-study [16].
The questionnaire “Benefits and harms of FMS-therapies” was delevoped by the heads of the clinical centers taking part in the study and by the directors of the two FMS self-help organisations. Similar to the NFA – questionnaire [14], survey participants were asked to "indicate whether you currently use any of the following interventions for FMS and if so, whether each helps to relieve your FMS symptoms". Moreover, the patients were asked if they had used these interventions in the past. Respondents rated the effectiveness (relief of symptoms) and harms (side effects) of each intervention used in the present or past on a 0 to 10 scale, with 10 being most effective (harmful). The interventions were listed in different sections: Self-management strategies (exercise, resting, physical modalities), psychological therapies, drugs and complementary/alternative medicine (CAM) (a copy of the questionaire is available on request). Face validity and understandability of the questionnaire were qualitatively validated by four clinicians (rheumatology, pain medicine, psychosomatic medicine) and 10 patients (integrative medicine, pain medicine) not involved in the study. Eight questioniare items were modified according to the validation reports.
The 4-item Patient Health Questionnaire-4 (PHQ-4) is an ultra-brief self-report questionnaire that consists of a 2-item depression scale (PHQ-2) and a 2-item anxiety scale (GAD-2). A score of ≥ 3 on the depression subscale represents a reasonable cut-point for identifying potential cases of major depression or other depressive disorders; a score of ≥3 on the anxiety subscale represents a reasonable cut-point for generalized anxiety, panic, social anxiety, and posttraumatic stress disorders [17]. We used the validated German version of the PHQ 4 [18].
Statistical analysis
The data were entered by four pairs of study assistants into a preconstructed data sheet. The entering of data was randomly checked by two authors, and further checked for plausibility during descriptive data analysis. Missing values were not replaced. Descriptive statistics were performed by Winstat for Excel (R. Fitch Software, Bad Krozingen, Germany, 2010).
Ethics
Study investigators respected the requirements of data protection and medical professional secrecy. The study was approved by the ethical committee of the Ludwig Maximilian Universität München.