Scientists at the Mayo Clinic have found that men with osteoarthritis in the knee experience more severe pain and more loss of cartilage if they smoke. Knee osteoarthritis is one of the leading causes of disability in older people.

    "This is a novel finding," said Dr. Shreyasee Amin, a rheumatologist and lead researcher in a new study that will be published online this week in the Annals of the Rheumatic Diseases.

    The knees of 159 men with osteoarthritis were imaged in the study and they were quizzed about their pain. On a pain scale with 100 as the highest score, the smokers came in at about 60 on average with the nonsmokers at 45.

    The researchers don't know why smoking exacerbates the arthritis. But they suggest smoking might disorder cells and inhibit cell growth and increase oxidant stress, which contributes to cartilage loss.

    Smoking could also raise carbon monoxide levels in blood, contributing to tissue hypoxia (insufficient blood oxygenation), which could impair cartilage repair.

    It is also possible that smoking lowers a person's pain threshold.

    Whatever the cause and connection, the scientists are excited because smoking is, as they term it, a "modifiable risk factor."

    In other words, stop smoking, and perhaps the joints will benefit.

    Another study suggests one way to quit is to cut back.

    Researchers looked at 19 previous studies and found that in 16 of them, cutting back combined with nicotine-replacement products led to an increase in the ability to kick the habit.

    "Cutting back is approved as a method of quitting in several European countries, but not in the United States," said study leader John Hughes, a professor of psychiatry at the University of Vermont College of Medicine. "Our review contradicts the commonly held belief that quitting requires stopping abruptly and provides evidence that smokers can quit successfully by reducing the amount of cigarettes smoked.

    "Furthermore, our review indicates cutting back is often a great way to start changing smoking that can lead to eventual quitting."

    (Agencies)