An Investigation of Nomothetic Versus Idiographic Assessment in Chronic Pain

Endometriosis, vulvodynia, and fibromyalgia are chronic pain conditions that cause great suffering. Despite the significant prevalence of all three conditions, they are receiving relatively little attention in psychological treatment research. Despite the popularity of methods that rely on aggregated group data, such as randomized controlled trials (RCTs), concerns have been raised in recent years about the generalizability of results from these methods to the individual level - group-to-individual generalizability. Since psychological treatments in the clinic are focused on enhancing the well-being of a specific individual this might affect how researchers should study these conditions. The current project aims to investigate: (a) item suitability for daily assessment of psychological variables, (b) group-to-individual generalizability in outcome measures frequently used in psychological studies and treatments of chronic pain, (c) relations over time between process and outcome variables, and (d) possible differences in results obtained across three pain conditions.

Endometriosis, vulvodynia, and fibromyalgia are chronic pain conditions that cause great suffering. The pain conditions are associated with suffering both psychologically and physically. However, knowledge about these conditions is scarce.

The present study aims to investigate the relationship between pain intensity, psychological flexibility, pain functioning, catastrophizing, and depressive symptoms in people with endometriosis, vulvodynia, and fibromyalgia. The investigators want to investigate how these factors relate to each other over time, but also whether there is a difference between people who are in contact with health care for these conditions and those who are not, and whether there is a difference depending on which of the included pain conditions one has.

Another aim of the project is to investigate whether the variables the investigators intend to measure meet the criteria for group-to-individual generalizability, meaning that group means and correlation coefficients based on aggregated group data also apply to individuals and that it is reasonable to draw conclusions about individuals from group data. Many psychological variables do not meet the criteria for this type of generalizability. By examining whether the results from variables can be generalized from a group level to an individual level, the investigators will gain clues about how much individualization is required in future research, assessments, and treatments for the pain conditions included in the current project.

In order to investigate group-to-individual generalizability, the project requires a large sample of participants to obtain group averages but also a large number of repeated measurements over a longer period of time for each participant. Repeated measurements from each individual are planned to be carried out to obtain individual mean values, in order to compare this with the group data. A diary will be created which is intended to be used daily, and a further aim of this study is to evaluate whether this diary is valid to use for future studies in these pain conditions.

On the first day of the study, participants will complete forms collecting demographic and background information, including information about the participants' pain.

On the first as well as the last day, information will also be collected from standardized questionnaires, including the Multidimensional Psychological Flexibility Inventory (MPFI), Patient Health Questionnaire-9 (PHQ-9), Brief Pain Inventory (BPI), and Pain Catastrophizing Scale (PCS).

On the second day of the study, participants will start to fill in twice daily measures at fixed times, and with a 12-hour interval between these two daily measurements. These are based on an ecological momentary assessment approach (EMA), where frequently repeated measurements are taken in the natural environment of the research subjects and where the time that participants have to think back on when answering is kept short. Using EMA, the within-individual variation can be easily monitored over time. The daily measurements will be collected for 42 days. The measurements consist of items from MPFI, BPI, PHQ-2, and PCS. In addition, two items are developed by the research team to assess sexual functioning and energy levels.

Participants will also fill out a weekly diary administered six times in total. The weekly diary consists of three items asking the participant to rate the previous week, and indicate whether something out of the ordinary has happened.

Eligibility Criteria:
Inclusion Criteria:

* Age 18 or over
* Reporting diagnoses of endometriosis, vulvodynia, or fibromyalgia
* The pain condition present persistently or recurrently during ≥ 3 months
* Access to an internet-enabled smartphone/tablet
* Fluent in written Swedish

Exclusion criteria:

- Planned surgery during the upcoming 6 weeks