The aim of this study was to examine whether 15-year trajectories of low back pain (LBP) and sciatica are associated with cardiovascular autonomic function in a large general population sample.
Previous studies using mainly small patient samples have suggested that LBP and sciatica are associated with abnormal cardiovascular autonomic function, namely altered heart rate variability (HRV) and baroreflex sensitivity (BRS). We examined this association in a large general population sample.
The data collections of the Northern Finland Birth Cohort 1966 consisted of pain questionnaires at 31 and 46 years (history of LBP, sciatica, and other musculoskeletal pains during the previous year; yes/no for each) and measurements of HRV and BRS at 46 years (heart rate, HR; root mean square of successive differences in beat-to-beat intervals, rMSSD; low-frequency systolic blood pressure variability, SBPV; cross-spectral BRS, BRS; each while seated and standing). The data collections also comprised several confounders. Trajectories for LBP, sciatica, and both together ("no pain," "decreasing," "increasing," "long-term pain") were constructed and general linear models were used to perform comparisons between trajectories (for HR/rMSSD, n?=?3398; for SBPV/BRS, n?=?1667).
In the crude models, LBP and sciatica were associated with higher HR, lower rMSSD, higher SBPV, and lower BRS, but these associations were mostly attenuated by adjustments. Regarding both LBP and sciatica, only the "increasing" trajectory was associated with two of the eight outcomes (standing SBPV, seated BRS) after adjustments. Regarding LBP, the "increasing" trajectory was associated with three (standing SBPV, seated BRS, standing BRS), the "long-term pain" trajectory with one (standing BRS), and the "decreasing" trajectory with one outcome (seated SBPV) after adjustments. Sciatica showed no association with the outcomes after adjustments.
We conclude that the 15-year trajectories of LBP and sciatica do not have a consistent independent association with cardiovascular autonomic function among the general population.