Well-being in pain questionnaire: A novel, reliable, and valid tool for assessment of the personal well-being in individuals with chronic low back pain

2.1 Development of the WPQ

Because subjective well-being is determined from positive subjective and personal experiences [1,2,3], the WPQ items were constructed to emphasize positive aspects of life (i.e. protective factors) instead of negative contributing factors and consequences of CMP. That is why the word “pain” was not included in the wording of items and was only mentioned in the title and introduction sentence “Well-Being in Pain Questionnaire (WPQ) is to screen the effects of pain on a person’s well-being.”

The original Finnish version of the WPQ and its first translation into English were developed by the first authors JM and FM. Both are native Finnish speakers. English is their other professional working language. Generation of the WPQ items was based on the combination of deductive and inductive methods as recommended in the study of Boateng et al. [34]. Deductive methods were based on an extensive literature review, academic background, clinical expertise, and feedback from field experts. Inductive methods included qualitative and cognitive pretesting of the WPQ items in a target population of CPM patients.

The author JM developed items 1–6 (items related to activities and rest), which were constructed based on the knowledge of profound importance of regular physical activity, subjective feelings of contentment, perception of general quality in life, and the quality of rest in subjects with CMP [7,14,15,16,17,18,19,20,21,22]. The author FM developed items 7–11, which were related to key elements of positive psychological functioning of feelings of optimism, freedom, closeness, contribution, and purpose [32,37,38]. Self-assessment over the last month was chosen because it was not considered to be too long and difficult to recall. JM is a long-term clinician and researcher of CMP and FM is a researcher of psychology, specializing in subjective well-being.

After the first Finnish version was drafted, a licenced professional translator and native English-speaker, specializing in healthcare texts, translated it into English. The translator also corrected the grammar and suggested some minor changes in the content of some items to increase readability. Then, the authors RN and LG evaluated the English version and provided feedback, which prompted some minor adjustments in some of the items. At that point, a provisional version of the WPQ was established.

Qualitative and cognitive pretesting and assessment of face validity of the provisional WPQ was performed with 30 CMP patients (specifically, CLBP) in the first author’s private clinic. These patients were informed about the details of the validation study and were asked to provide informed consent. They completed the WPQ at home and then gave verbal feedback about each WPQ item during the next clinic visit. The patients reported that the WPQ was easy to complete, the items were easy to understand, and the time frame (during the last month) was convenient to recall. After receiving this positive feedback about the appropriateness, content, and usability of the WPQ, it was agreed that the provisional version was the final version. The final version of the WPQ items is shown in Figure 1.

Figure 1

WPQ items. Each item is rated with a 5-point scale: “almost always” = 4, “often” = 3, “sometimes” = 2, “rarely” = 1, and “never” = 0.

2.2 Data collection

Data collection was carried out in two stages described in detail below. COSMIN checklist recommendations were used to make decisions about the number of participants needed for adequate statistical analyses, including internal consistency, known-group validity between subjects with CLBP and healthy pain-free controls, convergent validity, and structural validity [35]. Specific validity hypotheses were tested. First, we hypothesized that the total mean scores between the CLBP patients and healthy control subjects would be statistically different at a less than 0.05 significance level. Second, we hypothesized that convergent validity correlations between the WPQ and other CMP-related PROMs would be “≤0.4 or ≥−0.4.”

Subjects were recruited directly by the authors, other healthcare colleagues, and through study advertisements at Finnish spine and pain-related organizations. The study advertisements included information about the nature of the study, inclusion and exclusion criteria, and further instructions about how to complete all intake information and study PROMs at home.

The first stage of data collection included subjects with CLBP, which were collected through another registered clinical study (ClinicalTrials.gov Identifier: NCT05268822) [39] between 16th February 2022 and 20th October 2022. The recommended duration and frequency of CLBP were used to define CLBP in the present study [40]. CLBP was defined as “Low back pain present for more than three months and occurring more than three days per week” [41]. Written informed consent was obtained from all subjects with CLBP before the study.

The second stage of data collection included healthy control subjects, which were defined as “healthy subjects who did not report any persistent pain problems within the last month or pain at the moment of completing the questionnaires.” Subjects were recruited directly by the authors and other healthcare colleagues. Data collection was carried out between 14th January and 30th April 2023. The pain-free participants were informed about the study in a similar manner than the CLBP group, but additional information was provided about why written informed consent was not needed because according to the written decision of the University of Eastern Finland Research Ethics Committee, based on the Finnish National Board on Research Integrity guidelines.

Subjects were eligible for the study if they met the following inclusion criteria and not the exclusion criteria.

Inclusion criteria are as follows:

1. Males and females aged 18–68 years.

2. Subjects with low back pain lasting more than 3 days per week during the last 3 months or healthy subjects who reported no persistent pain problems within the last month nor having pain at when completing the questionnaires.

3. Proficient in written and spoken Finnish language.

4. Written informed consent was provided (subjects with CLBP only).

5. Completed pain history, demographics, and all PROMs.

Exclusion criteria are as follows:

1. History of malignancy.

2. Previous diagnosis of a neurological disease affecting the central nervous system (e.g., dementia, MS, etc.).

3. Previous diagnosis of a rheumatic disease (e.g., fibromyalgia, ankylosing spondylitis/rheumatoid arthritis, etc.).

4. Spinal surgery within 1 year of the study.

After the self-eligibility assessment of inclusion and exclusion criteria, the study participants completed study questionnaires on the webpages of Nordhealth Connect (https://connect.nordhealth.com/), which is a Finnish company providing an electronic platform with strong electronic authentication for data collection and storage of study questionnaires for participants. In Finland, strong electronic identification enables participants to verify their identity safely in various electronic services before completing PROM, demographic, and pain questions.

2.3 Demographic data and pain history

Each subject completed a structured set of web-based dichotomous (yes/no) questions about pain history. All subjects were asked demographic questions of age in years, height in centimetres, weight in kilograms, and educational level (1. Elementary school, 2. High school or vocational school, 3. Lower university degree, 4. Higher university). In the analysis phase, body mass index (BMI) was calculated using subject-reported data.

2.4 PROMs

1. The WPQ was designed to assess psychological, social, and lifestyle aspects of personal well-being over the last month. The WPQ utilized a 5-point Likert scale, including “almost always” = 4, “often” = 3, “sometimes” = 2, “rarely” = 1, and “never” = 0. A total score is determined by adding the results of each of the 11 items. Total scores ranged from 44 (the maximum well-being in pain) to 0 (the minimal well-being in pain). Note that the English version of the WPQ is not currently cross-culturally validated, and hence the English translation is not intended for use in clinical or research work without prior acceptable validation. The English and Finnish original full versions of the WPQ are included as supplementary materials 1 and 2, respectively.

2. The first part of the EuroQol (EQ-5D-5L) was used to assess five dimensions of health-related quality of life [42] – mobility, self-care, usual activities, pain/discomfort, and anxiety/depression – on a Likert scale (0 = no problems, 1 = slight problems, 2 = moderate problems, 3 = severe problems, and 4 = unable/extreme problems). The second part of the EQ-5D-5L enquired about self-rated health on a visual analogue scale between 100 “the best health you can imagine” and 0 “the worst health you can imagine” [42]. As a standard value set is not available in a Finnish population, a value set from a Danish population was used to calculate the index value, which is recommended by the EuroQol EQ-5D-5L User Guide [43]. EQ-5D-5L is one of the most commonly used PROMs of health-related quality of life in CMP populations [11].

3. The pain catastrophizing scale (PCS) is widely used and has been validated in different CMP populations [44]. It assesses the tendency to magnify the threat value of pain stimuli. Thirteen items are scored on a Likert scale from 0 to 4, producing total scores from 0 (no catastrophizing thoughts) to 52 (maximum catastrophizing thoughts) [45]. The PCS has been previously translated and validated in a Finnish CLBP population [46].

4. The Pain and Sleep Questionnaire Three-Item Index (PSQ-3) is a three-question questionnaire to evaluate the effects of pain on sleep. The three items are as follows: “1. How often have you had trouble falling asleep because of pain? 2. How often have you been awakened by pain during the night? 3. How often have you been awakened by pain in the morning?” The scale ranged from 0 (pain does not affect sleep) to 30 (pain has the maximum negative effect on sleep) [47]. The PSQ-3 has been translated into Finnish and validated in a Finnish CLBP population [48].

5. The CS inventory (CSI) assesses symptoms related to CS [49]. It is a two-part questionnaire in which part A contains 25 questions on CS-related symptomology using a Likert scale from 0 = never to 4 = always. The total score ranges from 0 to 100. Part B includes “No/Yes” and “year diagnosed” questions about previous diagnoses related to CS-related disorders. Part B of the CSI is to provide information only and is not scored [50]. Part B was not used in the present study. The CSI has been translated into Finnish and validated in a Finnish CLBP population [51].

6. The Generalized Anxiety Disorder Assessment (GAD-7) is a self-reported measure of symptoms related to generalized anxiety disorder. The items are rated over the preceding 2 weeks from not at all = 0 to nearly every day = 3. The total scale ranges from 0 (minimal anxiety) to 21 (the most severe anxiety) [52]. The GAD-7 has been adapted and validated in Finnish [53].

2.5 Statistical methods

Statistical analysis was performed using SPSS version 25 (IBM SPSS Statistics for Windows, Version 26.0. Armonk, NY: IBM Corp.). Statistical significance was defined as p < 0.05. Data were reported as n (%) or mean values with standard deviations (mean ± SD). Skewed distributed data were tested by the Mann–Whitney U-test. Categorical variables were compared by the likelihood ratio.

Convergent validity between the WPQ and other PROMs was calculated with Pearson’s correlation coefficient (r). The strengths of the correlations were interpreted as weak (<0.3), weak to moderate (>0.2 or <0.4), moderate (>0.3 or <0.7), moderate to high (>0.6 or <0.8), or high correlation (>0.7) [54]. Cronbach’s alpha was used to assess the internal consistency. An alpha value between 0.70 and 0.90 was considered acceptable [55]. A Kaiser–Meyer–Olkin (KMO) measure and Bartlett’s test of sphericity were used to test for appropriateness of the factor analysis. Unrotated EFA with maximum likelihood was used to identify the number of factors. EFA was recommended when there is no previous studies of the underlying factor structure of their measure [56]. The item loading cut-off value was set at ≥0.40, which is considered a “stable” value in the literature [57]. If the loading value was less than 0.40, the item was considered as “unstable” and hence is not a contributing factor [58].

3.1 Known-group validity

As shown in Table 1, all study questionnaire mean scores, including the WPQ, were significantly better (indicating less symptom severity) in the pain-free control compared to the CLBP subjects. As shown in Table 2, the inter-group comparison showed significant group differences in all WPQ items, except items 8 and 9. It was noted that no pain-free control subject provided an answer of “never” for any of the items. All items reflected increased well-being scores in the pain-free control group.

3.2 Internal consistency

Cronbach’s alpha showed acceptable results for the entire study group (α = 0.89) and separately for subjects with CLBP (α = 0.89) and pain-free controls (α = 0.75).

3.3 Convergent validity

As shown in Table 3, the WPQ demonstrated moderate correlations with PROMs of health-related quality of life, pain catastrophizing, sleep quality, CS symptoms, and generalized anxiety. Comparing the widely used health-related quality measure (EQ-5D-5L), correlations were stronger in the WPQ in 4 out of 5 comparisons including the EQ-5D-5L visual analogue scale.

3.4 Factor analyses

EFA was performed to determine the factor structure of the WPQ. The KMO and Bartlett’s test of sphericity results revealed that the sample size was sufficient (KMO = 0.88), and the items were appropriate (Bartlett’s test of sphericity: χ ² = 779.5, p < 0.01) for the factor analysis. Also, recommendations for suitability for the factor analysis of at least five subjects per item were met [59] as a total of 145 subjects and 11 items added up to 13.2 subjects per item.

The EFA indicated that factor 1 explained 48.9% (eigenvalue: 5.381) and factor 2 explained 11.69% (eigenvalue: 1.285) of the total variance of the WPQ. Hence, the eigenvalue ratio of factor 1 and factor 2 were 4.19, which met the ≥4 requirement for a one-factor model [60]. As shown in Figure 3, the eigenvalue ratio was visualized on a scree plot.

Figure 3

Scree plot.

As shown in Table 4, EFA factor loadings for a 1- and 2-factor analyses (items required factor loading ≥0.40) showed an acceptable fit for the one-factor solution. On the tested 2-factor model, none of the item loadings met the requirement of factor loading of 0.4 or more.