The epidemiology of low back pain in the general population and after motor vehicle collisions : population-based investigations

Abstract

The aim of this thesis is to describe the prevalence, incidence and course of adult low back pain (LBP) in the general population and after traffic collisions. The objective of Paper I was to determine prevalence of adult LBP and to document its severity. The objective of Paper II was to determine whether rear-end traffic collisions are associated with future health complaints, including LBP. Paper III concerns the incidence and prognosis for LBP after traffic collisions. Paper IV measures the incidence and course of LBP episodes in the general adult population.

Papers I and IV are based on the same study population. A random sample of 2,055 Saskatchewan adults received a health survey and 1,133 (55.1%) returned completed questionnaires. There was no evidence of selective response by LBP status. These subjects were followed at six and 12 months. Prevalence, incidence and course proportions were calculated and directly standardized to the source population. Paper II is based on a cohort of 4,124 Swedish adults. Drivers making claims for rear-end collisions were divided into those with whiplash (n=232) and those without (n=204). Drivers that had not been involved in a collision were randomly selected as the reference (n=3,688). The relative risks for future health complaints, including LBP, were determined seven years later. Paper III is based on an incidence cohort of all adult LBP traffic injury claims made in Saskatchewan over eighteen months (n=4,473). All claims were followed until claim closure, or censored at about two years. Health data were collected over a one-year followup period, and Cox models were built to investigate the impact of health recovery on claim closure and the effect of baseline variables on claim closure.

The point and lifetime prevalence of LBP in Saskatchewan adults was 28.4% and 84. 1 % respectively. The six-month prevalence of mild, intense and disabling LBP was 48.8%, 12.3 % and 10.7% respectively. There was little variation in prevalence across age groups, but women experienced more disabling LBP than men. The annual cumulative incidence proportion of LBP episodes was 18.6%. Only 26.8% of prevalent LBP cases resolved over the one-year follow up, and 40.2% of cases persisted with the same severity of LBP. The severity of LBP increased for 14.2% and improved for 36.1%. Of those that recovered, 28.7% had a recurrence of LBP within six months. Younger subjects had less persistent LBP and were more likely to have resolution.

Swedish whiplash claimants had a 70% increased risk of LBP seven years after their injury, but there was no increased risk in those exposed to a non-injurious rear-end collision. In Saskatchewan, 49.7% of all injury claimants suffered LBP, and claim closure times were strongly affected by insurance and injury-related factors, as well as other psychosocial factors (female sex, full-time employment and depression).

These results indicate that LBP is a common chronic disorder in the general adult population with a variable course marked by persistence, aggravation and recurrence. Whiplash injury to the neck is associated with future health complaints, including LBP. LBP commonly occurs after traffic collisions and its prognosis is influenced by a combination of biopsychosocial factors. These results indicate that LBP is an important public health problem.