"If you have lower back pain that is not explained by a spinal problem but is more of a muscle pain, things like obesity, alcohol abuse, smoking and depression, factors that you can affect, can be contributing to it," explained lead researcher Dr. Scott Shemory, an orthopedic surgeon with Summa Health System in Akron, Ohio.
Of all these risks, obesity is most obviously associated with back pain, he said. "It puts stress on all the joints and the lower back as well," he said. Also, smoking can decrease blood flow, which can also contribute to pain, he said.
As for depression, it might contribute to the pain. On the other hand, lower back pain might contribute to depression, Shemory said. The same can be said for alcohol dependence, he added.
However, Shemory said that these problems might cause people to be less physically active, which can increase pain.
But altering these behaviors can improve your overall health and may reduce lower back pain, he noted. However, the study only showed an association between these factors and lower back pain, not a cause-and-effect link.
"That's why preventing lower back pain is so important," he said. "In many cases, people just live with their pain."
The findings were to be presented this week at the American Academy of Orthopedic Surgeons annual meeting, in Las Vegas. Research presented at meetings should be considered preliminary until published in a peer-reviewed journal.
For the study, Shemory and his colleagues reviewed data on 26 million people, 1.2 million of whom had lower back pain. Overall, 4 percent suffered from the condition.
Lower back pain was most common among smokers (16.5 percent), alcohol-dependent drinkers (almost 15 percent), obese people (close to 17 percent) and those suffering from depression (slightly over 19 percent).
Dr. Jason Lipetz, chief of the division of spine medicine at the North Shore-LIJ Spine Center in Great Neck, N.Y., said, "This study of over a million patients with low back pain reminds us of the many interrelated factors which can contribute to this common complaint."
For example, cigarette smoking is known to accelerate degeneration of the lower spine, he said.
Obesity might reduce a patient's level of fitness. "What we do not know, however, is if the pain itself is limiting exercise and leading to more weight gain," said Lipetz, who was not part of the study.
"In addition, the relationship between mind and spinal pain is highlighted by an up to four times increase in lower back pain in patients with a history of alcohol abuse or depression," he said.