Our results suggest that the sensitivity and PPV of self-reported history of hysterectomy are high, implying that self-report is a valid means of collecting hysterectomy history. Approximately 91% of women who underwent a hysterectomy at an age less than 50 years reported that surgery as a reason why their menstrual periods had ceased on subsequent screening questionnaires; only 3% of women who self-reported a hysterectomy on their questionnaire had information in their medical records to suggest the continued presence of an intact uterus. We found no difference in the sensitivity of self-reported hysterectomy by history of bilateral oophorectomy, and no evidence to suggest that PPV or sensitivity of hysterectomy varied with time in the five to nine years following surgery.
With respect to bilateral oophorectomy, we observed a high PPV (100%) but low sensitivity (64%), suggesting underreporting of this surgery. Less than two-thirds of women with a documented bilateral oophorectomy performed before age 50 years reported on subsequent screening questionnaires that their menstrual periods had ceased due to a bilateral oophorectomy. PPV analyses found the validity of self-reported unilateral oophorectomy to be lower than for bilateral oophorectomy, and suggest that a substantial proportion of women who self-report having had a unilateral oophorectomy have actually had both ovaries removed. Greater than 60% of women who underwent a bilateral oophorectomy without hysterectomy over the study period self-reported cessation of menses resulting from a hysterectomy; while we cannot rule out the possibility that these women received a hysterectomy prior to the study period, the underreporting of bilateral oophorectomy as a cause of menopause remains concerning given that young women who receive a simple hysterectomy (i.e., without bilateral oophorectomy) may continue to experience ovarian cycling until bilateral oophorectomy, even in the absence of menstruation. However, given that some women may have already been postmenopausal at the time of surgery, underreporting of these surgeries does not necessarily imply underreporting of oophorectomy as a reason for cessation of menses.
There are several limitations inherent to the present study, mostly related to the design of the study questionnaire and the availability of information in medical records. With respect to our sensitivity analyses, we were not able to rule out the possibility that natural menopause, or menopause due to another reason, had preceded the documented surgery. Specifically, the questionnaire asked women to report the reason why their menstrual periods had ceased with no separate question inquiring on history of hysterectomy or oophorectomy. If women who did not self-report their documented surgeries failed to do so because they had undergone natural menopause before their surgery, our estimates of sensitivity will be conservatively low. Given that, in the absence of bilateral oophorectomy, approximately 80% of Caucasian U.S. women remain hormonally premenopausal through age 49,17
we attempted to minimize this conservative bias by restricting the present analysis to women aged less than 50 at the time of surgery. In fact, we observed that only 13% of women who had undergone a hysterectomy and did not report that surgery as a reason for their cessation of menses reported a natural menopause. Thus, while the proportion of women included here who will have undergone natural menopause prior to surgery is not negligible, we anticipate that the bias to sensitivity estimates due to inclusion of these women should be small.
Additionally, because our sensitivity estimates were limited to surgeries performed in 1996-2003 and women with surgeries prior to age 50, it is difficult to extrapolate to women with less recent surgical procedures. It is possible that the sensitivity of self-report wanes with time since surgery, although we found no difference in sensitivity estimates based on questionnaires completed at least five years following surgery and estimates based on the first questionnaires completed post-surgery.
There are several possible reasons for the observed underreporting / misreporting of oophorectomy history: 1) women may not know if / how many ovaries they have had removed, 2) women may have forgotten if / how many ovaries they have had removed, and 3) women may not understand that having both of their ovaries removed would result in the cessation of menses or, if they have also had a hysterectomy, may not understand the additional relevance of having their ovaries removed. Underreporting may also reflect issues with the design of the screening questionnaire if the wording and ordering of possible reasons for cessation of menses led fewer women to report their history of oophorectomy.
The primary limitation of our PPV estimations was the scarcity of information in medical records, even for women with surgeries reportedly performed in the past 15 years. There was no mention as to the presence or absence of ovaries in medical records of 21% of women who self-reported an oophorectomy, and such information had to be gleaned from transcribed medical histories for 37% of such women. Using information from medical histories in the absence of more concrete evidence may have biased estimates of PPV for menopausal surgeries, although PPV estimates did not markedly change after excluding women for whom the only source of information was a medical history.
We estimate a higher PPV for self-reported hysterectomy than previously suggested Brett et al.12
In a medical record review of 452 participants in the National Health and Nutrition Examination Survey (NHANES) who had reported no history of hysterectomy at baseline but reported a hysterectomy in a follow-up interview (1982-84, 1986, or 1987), confirmation from hospital records could be located for only 298 (66%). The fact that we observed a larger PPV than this study may suggest improved awareness among women with regards to understanding the nature of the procedure or increasing documentation in medical records; it may also reflect the fact that the present study was conducted in an integrated group practice setting where access to medical records is likely more complete.