Public defence: Henriette Jahre

Musculoskeletal pain is prevalent among adolescents and young adults, with neck pain as one of the most frequently reported pain locations. Musculoskeletal pain is a severe health concern with huge consequences for individuals affected and society. The etiology of neck and musculoskeletal pain among adolescents and young adults is not well known.

Increased knowledge of risk factors for neck and musculoskeletal pain in adolescents and young adults is necessary to facilitate targeted prevention and treatment interventions to reduce the high burden of musculoskeletal pain.

The overall objective of this thesis was to investigate the prevalence and risk factors for neck and general musculoskeletal pain in adolescents and young adults in population-based studies.

Methods

Paper-I

Paper-I is a systematic review identifying literature of risk factors for neck pain in young adults. Prospective cohort and registry studies of young adults (18-29 years of age) were included. A narrative synthesis of potential risk factors investigated in more than one study was conducted.

Paper-II

Paper-II is a prospective cohort study using data from the North-Trøndelag Health Study (HUNT) investigating risk factors and risk profiles (combinations of risk factors) for persistent neck pain in young adults. Potential risk factors were measured in adolescents aged 13-19 years in Young-HUNT3 (2006-2008), and the outcome, persistent neck pain, was measured in young adulthood 11 years later in HUNT4.

The sample was divided into two: Sample I included all participants, and Sample II included only adolescents with no neck/shoulder pain at baseline. Backward stepwise regression analyses were conducted to identify risk factors.

Paper-III

Paper-III is a cross-sectional study using data from The Norwegian Ungdata Survey (2017-2019) investigating the prevalence of neck/shoulder pain in isolation (neck/shoulder pain as the only pain site) and in co-occurrence with other musculoskeletal pain, headache, and depressive symptoms in Norwegian adolescents. The prevalence rates were presented for the total sample and stratified for school level and sex.

Paper-IV

Paper-IV is a prospective cohort study using data from The Fit Futures Study. The aim was to investigate if low social acceptance among Norwegian first-year high school students was a risk factor for persistent musculoskeletal pain two years later and whether psychological distress modified this association.

Social acceptance and psychological distress were measured in the first year of high school (2010/2011), and persistent musculoskeletal pain was measured two years later. Logistic regression and moderation analyses were conducted adjusted for sex and comorbidities. Main analyses were based on adolescents with no musculoskeletal pain at baseline, and secondary analyses on all included adolescents, regardless of pain status at baseline.

Results

The systematic review included six studies investigating 56 potential risk factors. Only five risk factors were measured in more than one study. Inconsistent results were found for female sex, computer use duration, and perceived stress. Physical activity and body mass index were not associated with neck pain in three studies.

Paper-II (HUNT) showed that female sex, low physical activity level, neck/shoulder pain, headache/migraine, back pain, and loneliness in adolescence increased the risk of persistent neck pain among all study participants (Sample I) (n=1433) 11 years later.

Female sex and perceived low family income increased the risk of persistent neck pain in young adulthood among participants without neck/shoulder pain at baseline (Sample II) (n=832). The risk profiles illustrated a cumulative increase in the probability of persistent neck pain by an increasing number of risk factors.

Paper-III (Ungdata) (n= 253,968) revealed a total prevalence of neck/shoulder pain of 24 percent, and only five percent had isolated neck/shoulder pain. Fifty percent of adolescents with neck/shoulder pain had co-occurring other musculoskeletal pain, and 50-70 percent had co-occurring headache.

Depressive symptoms were seen in 28 percent of boys and 45 percent of girls with neck/shoulder pain. In Paper-IV (Fit Futures) (n= 556), low social acceptance among peers was associated with persistent musculoskeletal pain two years later (Odds ratio=1.9, 95 percent CI 1.0-3.2). Levels of psychological distress did not modify this association.

Conclusion

This thesis found a prevalence of musculoskeletal pain, including neck pain, to range from 18-24 percent in Norwegian adolescents and young adults. Neck/shoulder pain seldom occurred in isolation but more often combined with other musculoskeletal pain, headache, and depressive symptoms. Girls had a higher prevalence of neck/shoulder pain than boys.

Risk factors for persistent neck pain in Norwegian young adults were female sex, neck/shoulder pain, headache/migraine, back pain, low physical activity level, loneliness, and perceived low family income. A higher number of risk factors increased the probability of persistent neck pain.

The thesis also revealed low social acceptance as a risk factor for persistent musculoskeletal pain in adolescents. These findings indicate that future research should have a broad perspective investigating risk factors for persistent musculoskeletal pain, and different combinations of risk factors should be explored further.

Clinicians and researchers should consider additional pain sites when assessing adolescents with neck/shoulder pain and be aware of the social aspect of musculoskeletal pain development.