Reproductive medicine journal, Human Reproduction, reports that women with endometriosis are significantly more likely than other women to suffer from a number of additional distressing or disabling conditions. These include a variety of autoimmune diseases, allergies, asthma, hypothyroidism, chronic fatigue syndrome and fibromyalgia.
Their findings are from the first population-based study in the world to investigate whether a range of other disorders are more prevalent in women with endometriosis - a condition in which the lining of the uterus (endometrium) grows in other parts of the abdominal cavity, attaching itself to organs and frequently causing pain, inflammation, bleeding and reproductive problems. It affects an estimated 8 to 10% of women of reproductive age.
The results - which confirmed there was typically a 10-year delay between onset of symptoms and a diagnosis of endometriosis - have prompted the researchers to urge doctors, especially those taking care of adolescents, to consider a diagnosis of endometriosis in girls and women complaining of pelvic pain and to watch out for other potentially serious conditions in these patients.
The research team from the National Institute of Child Health and Human Development in Bethesda, the School of Public Health and Health Services at George Washington University in Washington DC and the Endometriosis Association in Milwaukee, carried out and analysed a survey of 3,680 members of the Endometriosis Association,3 90% of whom were of reproductive age. All the women had surgically diagnosed endometriosis.
They found that among these women:
- 20% had more than one other disease
- up to 31% of those with co-existing diseases had also been diagnosed with either fibromyalgia or chronic fatigue syndrome and some of these additionally had other autoimmune or endocrine disease
- chronic fatigue syndrome was more than a hundred times more common than in the female US population generally
- hypothyroidism (under-active thyroid gland) was seven times more common
- fibromyalgia was twice as common
- the autoimmune inflammatory diseases - systemic lupus erythematosus, Sjögren's Syndrome and rheumatoid arthritis, and also multiple sclerosis, occurred more frequently
- rates of allergic and atopic conditions such as asthma and eczema were higher e.g. 61% of the endometriosis sufferers had allergies compared to 18% of the US general population, and 12% had asthma compared to 5%. If a woman had endometriosis plus an endocrine disease the figure rose to 72% and it was 88% if she had endometriosis plus fibromyalgia or chronic fatigue syndrome.
- Two-thirds of the survey subjects reported that relatives also had either diagnosed or suspected endometriosis, confirming research that suggested there was a familial tendency.
Lead investigator, Ninet Sinaii, from the National Institute of Child Health and Human Development, said: "As well as finding an increased prevalence of this wide range of diseases and conditions among women with endometriosis, we found that they reported significant pain and disability and, very worryingly, that there was typically a 10-year delay between the onset of pelvic pain and diagnosis."
Co-investigator, Dr Pamela Stratton, continued: "Since women appear to develop symptoms shortly after the onset of their periods and are not diagnosed for years, we don't know whether endometriosis actually occurs at menarche as others have reported or whether it develops over time. It's also unclear whether early treatment could prevent chronic pelvic pain from taking hold. It is vital therefore that attempts should be made to diagnose and treat endometriosis in adolescents."
Ms Sinaii said there were a number of limitations to the study, which could potentially introduce bias, including the relatively young age of the respondents, the fact that they were predominantly white, well-educated and members of a support group (therefore possibly atypical), problems with misinterpreting questions, recognising disease names, and so on.
Therefore, the researchers carried out a sensitivity analysis. This confirmed that even if the disease prevalence was underestimated in the general population and overestimated in the study sample, the rates reported in women with endometriosis were still significantly higher.
"These differences appear real," said Ms Sinaii.
She said the study was the first to provide data on the characteristics and co-existing states of women with pain from endometriosis.
"Women with endometriosis frequently suffer from autoimmune inflammatory diseases, hypothyroidism, fibromyalgia, chronic fatigue syndrome, allergies and asthma. It is evident that women with pelvic pain are not diagnosed as having endometriosis for many years, suggesting that physicians, especially those taking care of adolescents, should consider the diagnosis.
"These findings also suggest a strong association between endometriosis and autoimmune disorders and indicate the need to consider the co-existence of other conditions in women with endometriosis," she concluded.
