Background
Ankylosing spondylitis (AS) is a chronic inflammatory disease that affects the sacroiliac joints and spine of young adults, especially men (sex ratio 2:1) [
1] and its prevalence is most commonly reported to be 0.1 to 1.4 % depending on the population [
2]. People who are affected generally present at around 26 years of age, typically have inflammatory back pain and structural damage, resulting in joint stiffness and a gradual loss of spinal mobility [
2‐
4]. Male patients have more functional limitations and lower bone mineral density than female patients [
5]. Because of the early onset, related work disability, absence from paid work and socioeconomic burden to individuals with AS are substantial especially men [
6‐
8]. As these is no radical cure for AS patients at present, an important goal in treatment is to control the spinal inflammation and the resultant pain and stiffness [
9].
Subjective well-being (SWB), a popular concept in positive psychology, has gained increasing attention in medical science [
10]. Higher subjective well-being helps people to be more energetic, which is a vital component in recovery and treatment [
11]. With increasing progress in improving functional capacity and survival in AS patients, it is becoming increasingly clear that, for many AS sufferers, improving the quality of life is equally as important as the survival benefit provided by pharmacological treatment. SWB refers to subjective and multidimensional evaluation of daily life [
12,
13], which can be measured by the General Well-Being Schedule (GWBS). GWBS is a generic instrument, which covers the most central dimensions of subjective health and applies to diseased populations and healthy people. As we all know, there are many schedules regarding quality of life such as EuroQol (EQ-5D) or Short Form-36 (SF-36). However, the above schedules include physical components and mental components, which are used to reflect physical health and psychological health respectively [
14,
15]. Compared with EQ-5D or SF-36, the General Well-Being Schedule (GWBS) is a brief indicator of subjective feelings of psychological well-being and reflects mental health totally [
16]. Furthermore, there are many studies about SF-36 evaluation in AS patients, but few about GWBS. Our team has verified the health-related quality of life of ankylosing spondylitis patients assessed by SF-36 [
17]. Thus, we choose the GWBS in this current study.
The previous studies on subjective quality of life mainly aimed at healthy people, empirical knowledge on the subjective health of AS patients is relatively scarce. The aim of this study is to assess the SWB in patients with AS compared with the healthy controls, and to investigate the relationship of various domains of SWB with demographic characteristics, disease-specific variables in AS.
Discussion
In this study, we aimed to determine which variables affect the SWB assessed by GWBS survey in AS patients. The significant correlation in the AS group was obtained between the four variables (sleep quality, Family-APGAR, BASDAI, therapy prospect) and SWB.
Firstly, in this Subjective Well-being survey, patients with AS reported significantly impaired health on all scales of GWB except for the O scale, compared with the healthy controls. Age and sex ratio are comparable in the two samples, thus, we consider that SWB may be affected by the AS disease.
Secondly, the results of single factor analysis in the AS patients indicated that SWB may differ significantly between two subgroups of residence. In addition, the SWB of physical workers differed significantly from the SWB of mental workers. However, when analyzing demographic variables in the healthy population, age, marital status, family income and occupation have been found to be associated with the total score of SWB (
P = 0.004,
P = 0.001,
P = 0.003,
P = 0.013). That is to say, demographic variables do not appear to have much of an impact on SWB in the AS patients, which is consistent with the previous study in healthy people [
26]. Study on patients attending community-based mental health services reported that demographic variables explained only 2.9 % of the variance in subjective quality of life [
27].
Thirdly, the regression analyses revealed that subjective well-being was positively associated with better sleep, lower disease activity and more family care, therapy prospect. Occupation and place of residence were excluded from the regression equation, which highlighted the fact that demographic variables did not play a crucial role in the well-being of AS patients.
We observed that 23.5 % of participants suffered from sleep disorder, and sleep quality, which should not be ignored, has been found to affect SWB in AS patients. In addition, some results have also been reported that there was a higher rate of sleep disturbance in patients with AS [
28,
29], which were important concerns in patients with AS [
30]. In agreement with these findings, recent studies [
31,
32] have suggested that poor sleep can impair well- being, most of these studies have involved individuals’ perceptions of sleep quality and duration. However, Jean-Louis and colleagues [
33] found no association between sleep quality and SWB in adult general population. Sleep disturbance is often produced by inflammatory pain [
5,
34]. Also, mental as well as physical aspects were affected due to the poor sleep quality [
35]. Consequently, it is not hard to follow the relationship between sleep quality and SWB in this study. We all know that, poor sleep quality can aggravate the patients’ condition, which is unfavorable for the recovery of the disease. Sleep disturbance is frequently complained by patients with AS and is still largely ignored by clinical care and research [
36]. Thus, we should pay great attention to the patients’ quality of sleep, to examine the independent risk factors of sleep quality and to improve sleep quality in AS patients.
Family function is what family performs on the behalf of its members in a larger society and it is assessed by APGAR [
37]. In our study, family function appeared to be related to SWB in AS patients. Previous study suggested that family function had much effect on quality of life and well-being [
37]. Likewise, Andrea reported that family ties had significant and positive associations with psychological well-being [
38]. Kenneth et al. [
39] also confirmed that family function in women with rheumatoid arthritis is related to subjective well-being, beyond the pain and fatigue associated with SWB. To our knowledge, Family care or Family-APGAR to some extent can help us cope with stress, anxiety and various emergencies, which could influence SWB. It should be considered as a determinant of health to improve subjective well-being. In addition, BASDAI has a negative relationship with the variable of subjective well‑being. BASDAI addresses disease activity which definitely affects quality of life, thereby, it is reasonable to draw such a conclusion. The conclusion is highly consistent with Bing Han’s research indicating functional capacity as predictor of psychological health [
40], as well as the study of Geertzen which concluded that the influence on SWB was less when patients were physically independent [
41]. Based on the findings of the present study, positive attitudes towards therapy prospect leads to higher well‑being of the patients with AS. To our knowledge, it is necessary to stay positive and then to be helpful to our state of mind.
Lastly, there are some limitations of our study. First, we recruited AS patients from one hospital, even though the hospital has a wide audience in the province, findings of this study cannot be generalized to all AS patients in our society. Second, it was a cross-sectional design and therefore can only be used to draw conclusions based on the relationships among variables. Longitudinal studies should be performed to identify the effects found in the present study. Third, although we have found sleep quality had significant correlations with SWB, many influencing factors of sleep quality should be explored. Last, we did not consider the relationship between SWB and kinds of drugs patients accepted, which should be verified in further studies.
Acknowledgements
The study was supported by grants from the National Natural Science Foundation of China (30771849, 30972530, 81273169, 81573218, and 81571572). The authors would like to thank Anhui Medical University for providing samples for the study. The authors would also like to thank the participants who cooperate with our team.