Gender differences in ankylosing spondylitis

Via About.com Arthritis, a clinical study examining the influence of gender on the severity of ankylosing spondylitis. The study looked at 302 men and 100 women who had AS for more than 20 years. The women had an earlier onset of disease, were more likely to have a first-degree family member with the disease, and had more peripheral symptoms. But the study also observed the following:

1. Radiographic spinal damage was worse among men.
2. Functional disability was the same among men and women.
3. After adjusting for radiographic spinal damage, women reported worse functioning.

I'm having trouble understanding what that means -- and it's probably beyond the scope of any medical study to infer general conclusions from such data. But these data suggest to me a discrepancy: either the disease is worse in women for a given level of spinal damage (although, on average, the men were in worse shape -- median scores of 10 vs. 6.5 -- just that a woman with 6.5 would report worse functioning than a man with 6.5), in some as-yet unquantifiable way, or women are overreporting/men are underreporting their symptoms.

Something subtler, I hope, than "women bitch more about pain," but I recall a study a few years back -- I'm too tired to look for a link at the moment -- that said that if men and women reported the same amount of pain, the men got more medication for it, on the assumption that women were more likely to complain and men were more likely to suck it up. Now, I'm male and a big wuss and I complain all the time, so I'm leery of stereotypes and would hate to see them confirmed, but you know ... how do you explain worse self-reported functioning for the same observed data?