Sinaii, N, SD Cleary, ML Ballweg, LK Niewman and P Stratton. 2002. High rates of autoimmune and endocrine disorders, fibromyalgia, chronic fatigue syndrome and atopic diseases among women with endometriosis: a survey analysis. Human Reproduction 17:2715-2724

This study reveals that women with endometriosis are much more likely to also suffer from a cluster of other autoimmune and endocrine disorders than are women in the general US public. Allergies, asthma, chronic fatigue syndrom, lupus, hypothyroidism and other diseases were far more common in endometriosis sufferers. The study also document significantly greater infertility among women with endometriosis.

This research is important for two reasons. First, it puts endometriosis patients, their families and physicians on the alert for other health problems that accompany endometriosis. Second, it reinforces the emerging scientific sense that endometriosis is a disease of the immune and endocrine systems.

It also raises the possibility that this collection of disorders may share in part or in whole some common mechanisms or causes. Because of strong indications implicating dioxins in the etiology of endometriosis via disruptive impacts on the immune and endocrine systems, the pattern of co-occurrence of disease revealed by this paper suggests dioxins' role in these other diseases should be studied, also.

What did they do? Sinaii et al. mailed a questionnaire to approximately 10,000 members of the Endometriosis Association to obtain data on other health problems they had or were experiencing. The analysis was limited to responding endometriosis patients whose condition had been confirmed surgically. The survey obtained basic demographic information as well as health data reflecting disease and reproductive history. Disease status was dependent upon diagnosis by a physician, except for asthma, eczema and allergies. Family histories of endometriosis were also obtained.

What did they find? Among the 4000 questionnaires analyzed, 3680 were from women confirmed surgically to have endometriosis. Compared to the general public, respondents were more likely to be white, have a higher income, be college-educated and be of reproductive age. This reflects the fact that members of the Endometriosis Association must pay annual dues and have the time, inclination and education to seek out the Association. Women with higher income may also be more able to afford a surgical diagnosis for endometriosis.

Their data revealed that on average, it took 10 years from the first onset of pelvic pain to an actual diagnosis of endometriosis.

Infertility rates of questionnaire respondents averaged markedly higher than the US population overall. By separating the respondents into different age groups (figure below), it can be seen that this difference becomes apparent with age.

No differences were observed among women from ages 15 to 24. Infertility was lower in the general US population from ages 25 to 44 ( p < 0.001). Women with both endometriosis and either endocrine disease or fibromyalgia and chronic fatigue syndrome showed less infertility than endometrioisis alone. .

As evident in the table below, Sinaii et al. found striking patterns of co-occurrence of a variety of disorders. Women with endometriosis are far more likely to also have several autoimmune inflammatory diseases, endocrine diseases and chronic pain and fatigue states: for example, almost 21 times more likely to have lupus, 7 times more likely to have hypothyroidism, and 180 times more likely to have chronic fatigue syndrome.

Immune system abnormalities were also more prevalent among women with endometriosis, and even more so if they had additional disease.

What does it mean? Any self-reporting survey has limitations that make it important to be cautious in reaching conclusions. Sinaii et al. carried out a series of sensitivity analyses to ask, in essence, "how wrong would the survey results have to be to change the qualitative nature of the results." The answer: dramatically so, more than is likely to result from errors that may or may not have been introduced by the study procedure.

In essence, the clear qualitative pattern is that endometriosis travels together in a pattern of diseases involving the endocrine and immune systems. Women with endometriosis are clearly at risk to these other disorders. Women, families and physicians should be alert to the clues that the presence of endometriosis gives for other diseases, and vice-versa. Informed vigilance may shorten the decade or longer that often drags on between onset of endometriosis and diagnosis.

This research also raises the possibility of shared causal factors among these different diseases. Research pursuing this hypothesis is clearly warranted. Because of strong links between dioxin and endometriosis, the enormous odds ratio reported here for endometriosis and chronic fatigue syndrome raises the plausibility of suggested links between chronic fatigue and dioxin.