RECENT WORK-RELATED ACTIVITIES AND THE ONSET OF FIRST-TIME LOW BACK PAIN : A CASE-CONTROL STUDY OF THE NEW YORK CITY FIREFIGHTERS

Iman  A. NUWAYHID

The onset of occupational Low Back Pain (LBP) has been associated either with exposure to acute activities of sufficient magnitude to cause instantaneous damage to the lower back tissues or exposure to cumulative long‑term repetitive or static spinal loading. The delay in the onset of pain following an acute exposure and the role of cumulative short-term exposures, however, has not been addressed. Incident cases of first‑time LBP among the New York City firefighters and a random sample of unmatched controls were concurrently interviewed to determine if the onset of LBP is associated with exposure to single activities or the cumulative effects of a group of activities performed during the last working shift.

Operating a charged hose inside a building (OR= 2.41, 95% CI=0.91‑6.36), breaking windows (OR = 4.60, 95% CI= 1.83‑11.58), looking for hidden fires (OR=4.97, 95% CI= 1.66‑14.83), and lifting objects heavier than 40 pounds (OR= 2.61, 95% CI= 0.92‑7.34) were associated with the onset of LBP after adjusting for long‑term risk factors (age, rank, previous job, steps climbed) and off‑duty activities. Paradoxically, activities such as pulling booster tank hose, participating in multi‑unit drill, and participating in physical training were associated with a significantly reduced risk of LBP even after adjusting for the same risk factors. This could be related to the prolonged time control firefighters spent in the less hazardous zones. Upon dividing the firefighter's workplace into five work zones, a gradual increase in the risk of LBP was noticed as the firefighter approached a structure. The odds ratio increased to 4.89 when the firefighter was working inside a structure. Moreover, the risk of LBP among ladder firefighters increased with the number of activities performed fighting a structural fire. However, the lack of real‑time exposure to activities precluded the creation of a valid cumulative measure. After adjusting for exposure to smoke, a surrogate of severity of alarms, only activities and zones, with increased risk lost their significance. Whether smoke exposure represented environmental hazards or strenuous conditions of work could not be discerned.

Changes in individual and workplace practices and further research into the role of activities utilizing a suggested unified model were suggested.