Online Self-management in Fibromyalgia

A visual analogue scale (VAS) from 0 to 10 will be used to measure pain coping, with higher scores indicating better pain coping. The primary endpoint is the difference in change in pain coping between patients in the intervention and control condition from baseline to post-intervention (immediately after the intervention).

A VAS from 0 to 10 will be used to measure well-being, with higher scores indicating better well-being.

Illness cognitions will be assessed by the Illness Cognition Questionnaire (ICQ; using Helplessness and Acceptance scales). Items are scored on a 4-point Likert scale ranging from "not at all" to "completely". Higher scale scores reflect greater use of the assessed construct.

Pain coping strategies will be assessed by the Pain Coping Inventory (PCI) that comprises six scales, namely, Pain Transformation, Distraction, and Reducing Demands (three active pain coping strategies), and Retreating, Worrying, and Resting (three passive pain coping strategies). Items are scored on a 4-point Likert scale ranging from "hardly ever" to "very often". Higher scale scores reflect greater use of the assessed pain coping strategy.

Illness perceptions will be assessed by the Illness Perception Questionnaire (IPQ-R). The Identity scale consists of the sum of yes-rated items (patients rate whether they believe certain symptoms to be related to their illness). Furthermore, the remaining scales described below are rated on a 5-point Likert type scale ranging from "strongly disagree" to "strongly agree". High scores on the Timeline Acute/Chronic and Cyclical, Consequences, and Emotional Representations scales indicate beliefs about the chronicity and cyclical nature of the illness, the negative consequences of the illness, and patients' emotional experience of their illness. High scores on the Personal and Treatment Control and Illness Coherence scales reflect positive beliefs about perceived control and an understanding of the illness.

A VAS ranging from 0 to 10 will be used to measure pain, with higher scores reflecting more severe pain.

Part 1 of the Multidimensional Pain Inventory-Dutch Language Version (MPI-DLV) will be used with Interference and Pain Severity scales and as exploratory measures Support, Life Control, and Affective Distress. Items are rated on different 7-point Likert scales, with higher scores reflecting greater intensity in a subscale.

Health-related quality of life will be assessed with the RAND-36, which consists of 36 items that are averaged, resulting in eight health scale scores, namely Physical Functioning, Role Limitations due to Physical Health Problems, Role Limitations due to Personal or Emotional Problems, Social Functioning, Emotional Well-being, Energy/Fatigue, Bodily Pain, and General Health Perceptions. The questionnaire also includes one item on perceived change in health. Besides, physical and mental health composite scores will be calculated. Higher scores reflect more favorable health states.

The Fibromyalgia Impact Questionnaire (FIQ) consists of 10 self-rated items covering the impact of fibromyalgia on different aspects of functioning and well-being. Total scores range from 0 to 100, with higher scores reflecting worse fibromyalgia impact.

Health-related quality of life will be assessed by the Five-Level Version of the EQ-5D (EQ-5D-5L). In this questionnaire, 5 dimensions are measured in 5 items: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. A 5-point Likert scale ranging from "no problems" to "extreme problems" is used for every dimension, with higher scores reflecting more problems in a dimension. A VAS ranging from 0 to 100 (0 = "The best health you can imagine" to 100 = "The worst health you can imagine") is applied as well, with higher scores indicating a better health state as perceived by the patient.

The intervention will be economically evaluated with the Five-Level Version of the EQ-5D (EQ-5D-5L). Five items cover 5 dimensions of health-related quality of life: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. A 5-point Likert scale ranging from "no problems" to "extreme problems" is used in the questionnaire, with higher scores indicating more issues in a dimension. The 5 dimensions can be summed into a health state and utility values can be calculated for these health states.

The intervention will be economically evaluated with the iMTA Medical Consumption Questionnaire (iMCQ), which measures health-care utilization.

The intervention will be economically evaluated with the iMTA Productivity Cost Questionnaire (iPCQ). Productivity losses are assessed in three modules in this questionnaire, so that certain types of productivity losses can be omitted when these are not applicable to a population.

The experience and satisfaction of patients with the intervention, and the perceived effect of the intervention will be assessed with an evaluation questionnaire comprising various numerical rating scales, Likert scales, and open questions.

The Internet-specific Therapeutic Relationship Questionnaire (ITRQ) will be used to assess the expected/perceived patient-provider interaction. The ITRQ comprises 10 items that are measured on a 10-point Likert scale ranging from "totally disagree" to "completely agree". The questionnaire consists of two scales (Internet-specific Time and Attention and Internet-specific Reflection and Comfort) and a total score. Higher scores reflect a stronger therapeutic relationship.