Generalised joint hypermobility and shoulder joint hypermobility, – risk of upper body musculoskeletal symptoms and reduced quality of life in the general population

Musculoskeletal symptoms like pain, ache and discomfort is a burden for society due to its enormous societal costs. One of the musculoskeletal conditions, Generalised Joint Hypermobility (GJH), is a hereditary condition with an exaggerated ability to exceed the joints beyond the normal range of motion, defined by a certain number of positive joint mobility tests [1]. GJH has been found to be associated with musculoskeletal pain [2, 3], fibromyalgia [4], anxiety [5, 6], and musculoskeletal injuries [7]. GJH is even anticipated to be a risk factor for premature osteoarthritis [2], but this has never been confirmed.

Prevalence rates of adults with GJH measured clinically vary from 2% to 57% and these are dependent upon the test and criteria used, and the population investigated [2, 8]. High prevalence rates of GJH have been identified within specific sports/performing art activities, such as ballet dancing, gymnastics, swimming, and among musicians [9–12]. Most studies reporting prevalence of GJH include study samples from specific ethnic areas, age groups, or participants from specific health care clinics. But prevalence rates of GJH in a general adult population are lacking.

Tests for classifying GJH by clinical tests are the Beighton score, consisting of nine tests of satisfactory reproducibility [1, 13, 14]. For use in epidemiological studies, a validated questionnaire, the Five-part Questionnaire (5-PQ), has been developed taking actual, as well as historical information of hypermobility into consideration [3, 15, 16]. Using the 5-PQ the British population prevalence of GJH was 18% (based on physician consultations of 46,000 adults already included in a study of chronic widespread pain) [17], and 37% (based on 2,523 Brazilian university students) [15]. Due to the current prevalence rates being based only on selected populations, there is a need for a solid estimate of the prevalence in a random sample of the general adult population.

Previous studies have found an association between GJH and self-reported shoulder injuries in adult patient populations (e.g. Joint Hypermobility Syndrome and Ehlers Danlos Syndrome, Hypermobile Type) [18, 19], patients from emergency units with GJH/GJH with shoulder joint hypermobility (GJHS) and traumatic shoulder injuries [20], and in non-patient populations like military personnel [21], and adolescents with GJH [22]. Again, these associations were primarily studied in selected populations. In the general working population one of the contributors to neck/shoulder symptoms is reported to be work-related exposure [23, 24], but GJH/GJHS as another potential contributor to neck/shoulder symptoms in the general population is yet to be explored.

In summary, since former studies have reported prevalence of GJH, and an association between GJH and musculoskeletal symptoms using selected study-samples well known in the health care, there is potential risk of over-reporting. Therefore, the aim of this study was to determine the prevalence of GJH and GJHS in the general adult population in Denmark, and further investigate the association of GJH/GJHS with musculoskeletal symptoms in the upper part of the body, as well as with HRQoL.

The estimated prevalence was 30% for GJH and 5% for GJHS. Compared with NGJH, participants with GJH and GJHS had higher odds for upper body musculoskeletal symptoms within the last 12 months (mostly in the shoulders and hands/wrists), and higher odds of being prevented from performing their usual activities in/outside their home (mostly due to neck and shoulder symptoms). Furthermore, GJH and GJHS had increased OR of 2.2-3.1 for upper body musculoskeletal symptoms in all regions lasting for more than 90 days (except in elbows), and both groups had increased OR for reduced HRQoL (except for anxiety/depression). Most OR for GJHS were about twice as high as for those having GJH alone.

Compared with other countries, the current prevalence of 30% is similar to a Brazilian study of university students that reported a prevalence of 37% using the 5-PQ (and in the same study 34% using the Beighton score of at least 4/9) [15]. However, the present prevalence is higher than a British survey of adults reporting a prevalence of 18% also using the 5-PQ [17]. This may be due to the participants in the British study were older than in the current study (median of 55 years versus 50 years in the current study), and thus recall bias of previous hypermobility abilities may have been different in the two studies, in addition to the fact that people become less hypermobile with age [2]. An uneven sex ratio (in all 56% women) is also likely a contributing factor to the higher estimation of GJH in the current study, because the prevalence of GJH is higher in women than in men [2]. However, the current sex ratio was similar to both the British and the Brazilian studies [15, 17]. The prevalence of GJH is furthermore known to be higher in non-Caucasians [43]. The Danish proportion of immigrants and their descendants (non-Caucasians) did only account for 11.6% of the total population at the time of the study, making the current study population fairly homogeneous with respect to ethnicity (Statistics Denmark, 2015). Thus a higher rate of non-Caucasians seems not likely to be a reason for the higher prevalence of GJH in Denmark than in the UK.

The prevalence of GJHS was 5%, but to our knowledge there has not been another study that has examined the prevalence of shoulder joint hypermobility in combination with GJH. Since neither the most often used clinical tool for classification of GJH (the Beighton score), nor the 5-PQ include a specific test/question for shoulder joint hypermobility, the current addition of a question targeting specifically the shoulder provides information that was previously unknown.

Generally, participants with GJH were significantly more likely to report musculoskeletal symptoms in the upper part of the body than NGJH. This is similar to previous studies that reported significant associations with musculoskeletal symptoms in GJH compared with NGJH [2, 8, 17, 18]. The severity of musculoskeletal symptoms was obvious in the current study, illustrated by the high proportion of participants with GJH/GJHS being prevented from performing their usual activities, and the proportion reporting chronic musculoskeletal symptoms (more than 90 days per year). The most frequent body regions preventing participants with GJHS from performing their usual activities (in/outside home) and with more than 90 days of symptoms were the shoulder and neck regions, possibly due to the hypermobile shoulder condition. Although GJH is a well-known risk factor for joint dislocation and soft tissue injuries (e.g. muscle, tendon and ligament injuries) [2], the information of the high presence of musculoskeletal symptoms among participants with GJH in Denmark and especially GJHS is new. It was anticipated that GJHS would be associated with musculoskeletal symptoms, especially in the shoulder, and this was mostly confirmed in the current study. Not surprisingly, participants with GJHS had about three fold higher odds of musculoskeletal symptoms in the shoulder and neck than NGJH. Symptoms in all other upper body regions could be due to compensatory movements resulting in overload.

The low HRQoL scores in participants with GJH are in agreement with a previous study of patients diagnosed with Ehlers Danlos Syndrome, Hypermobile Type [19], but even lower HRQoL in participants with GJHS has not been previously reported. Both patients diagnosed with shoulder instability and more severe conditions of hypermobility (e.g. Joint Hypermobility Syndrome and Ehlers Danlos Syndrome-Hypermobile Type) have been found to be associated with severely reduced HRQoL compared with NGJH [18, 44], which seems to support the current reduced HRQoL, especially in those with GJHS. Noteworthy and surprisingly, the EQ-5D-5 L’s physical activity dimension had the highest OR for decreased HRQoL in participants with GJHS. This underlines the high physical impact GJH and GJHS has on participants’ life. The current study found no associations for GJH and GJHS with the mental-related dimension of anxiety/depression, which has previously been reported in patients with Ehlers Danlos Syndrome, Hypermobile Type [19]. However, a recent study did also find no significant association between patients with Joint Hypermobility Syndrome/Ehlers Danlos Syndrome, Hypermobile Type and mental health, thereby supporting the current results further [18]. One of the reasons for the conflicting results of the impact GJH has on mental health [19] may be due to different methods of measuring mental health (the current one dimension of the EQ-5D-5 L versus the previously used four dimensions in SF-36).

The current response rate of 49% was fairly high, given only two reminders, and that the participants had to initiate the response to the electronic questionnaire, and it was actually higher than in the mentioned British population-based study (28%) [17]. Since the study had a focus on joint hypermobility, participants with no signs or knowledge of hypermobility may have been less likely to answer the questionnaire, with a risk of overestimating the prevalence. Unfortunately, since the random sample only included names and home addresses, no drop out analyses could be performed on demographics. However, previous studies using the same method (no aggressive protocol, no incentives, no sponsor sender, the national survey) have shown no response rate bias with regards to low response rates and skewed demographics (age, sex, marital status, education) [45, 46].

Selection bias was anticipated not to have influenced the results in relation to musculoskeletal symptoms and HRQoL, since the 12-month prevalence of musculoskeletal symptoms and activity limitations for the participants were in accordance with previous studies [17–19, 22], as was the distribution of responses to the HRQoL [18, 39, 40, 47, 19]. With the relatively long recall periods for both GJH (5-PQ: ever/now) and musculoskeletal symptoms (SNQ: last 12 months) recall bias may be present, but this does not seem likely, since satisfactory psychometric properties (reliability and validity) have been reported for both 5-PQ and SNQ [3, 15, 30, 32].

Although previous studies have investigated HRQoL and musculoskeletal symptoms in participants with Joint Hypermobility Syndrome/Ehlers Danlos Syndrome, Hypermobile Type, no previous study has used the SNQ and EQ-5D-5 L in a population-based study of GJH and GJHS. This makes it difficult directly to compare the current data with other studies.

The strength of this study was the random selection of the study sample at the population level and the extraction of data through a governmental institution, which resulted in a representative sample of adults living in Denmark during the study period. Furthermore, with the exception of the additional question on GJHS, only validated questionnaires were used in the current population-based survey [3, 40, 48–50]. Since both unadjusted and adjusted models showed almost the same pattern of significance, the current findings and associations appear to be consistent.

GJH and GJHS are frequently self-reported musculoskeletal conditions in the general adult population. Compared with NGJH, GJH and especially GJHS present with higher odds and severity of upper body musculoskeletal symptoms and decreased HRQoL. Also, there is a need to study the prevalence of GJH including lower extremity hypermobility and the association to lower body musculoskeletal symptoms. Further, since the current study is a cross-sectional study, longitudinal studies are recommended to describe the onset, fluctuations and persistence of chronic musculoskeletal symptoms and osteoarthritis in the general adult population, and how musculoskeletal symptoms are associated with GJH through the life course.