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ORIGINAL RESEARCH |
From the Departments of *Health Policy, Medicine, Biomathematical Sciences, and Obstetrics and Gynecology, Mount Sinai School of Medicine, New York.
Address reprint requests to: Nina Bickell, MD, MPH, Mount Sinai School of Medicine, Department of Health Policy, 1 Gustave L. Levy Place, Box 1077, New York 10029; e-mail: Nina.Bickell{at}mssm.edu.
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ABSTRACT |
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METHODS: We reviewed inpatient, clinic, and physician office charts of 221 women with tubal pregnancy. We assessed the conditional risk of rupture with passing time and other factors related to rupture.
RESULTS: Time between symptom onset and treatment varied from 3 hours to 66 days with an average of 7 days. There was a 32% rupture rate. The conditional risk of rupture was highest within the first 48 hours of symptom onset (5–7%). The risk dropped, leveled off, and remained fairly steady at approximately 2.5% per 24 hours of untreated symptoms. Classic tubal pregnancy signs, symptoms, and tests were not helpful in predicting rupture.
CONCLUSION: The rate of rupture is highest in women with the shortest times between symptom onset and treatment. With passing time, the risk declines, but remains steady despite women's getting into care.
LEVEL OF EVIDENCE: II-2
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METHODS |
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Detailed information about time, clinical signs and symptoms, diagnostic evaluations, and treatments were obtained from medical records. We tracked back to each patient's first encounter with the medical system for this ectopic episode. In addition to hospital emergency department, ambulatory surgery and inpatient records, 103 physician offices and outside clinical sites provided medical record data about patients’ initial examinations.
Total time is defined as the time between symptom onset and receipt of definitive treatment. Patient-time, a subset of total time, is the period between the time a patient first noticed abnormal symptoms and the time she was first examined by a physician for these symptoms. System-time occurs between the time of first examination and the time of definitive treatment. The factors that affect the amount of time between symptom onset until patients have accessed medical care likely differ from those that affect the time between the first medical examination and surgical treatment.10
We determined the times at which physicians performed physical examinations by abstracting data from physicians’ notes, nursing notes documenting the physicians’ examinations and medication order forms. For example, time of definitive treatment was the time the treatment was administered as noted in physician or nursing notes. If methotrexate was the definitive treatment, the time it was first administered was used. Similarly, if surgery was the definitive treatment, we used the time surgery started as indicated on the anesthesia report. Exact times of physician examinations were recorded in 83% of patient charts. For examinations without documentation of time, we used the time midway between documented timed set points. For example, if a patient was first examined in the emergency department at 4:00 am, transferred to the operating room at 8:00 am and examined by a gynecologist in between, we estimated that the gynecologist's examination occurred at 6:00 am. For untimed office examinations, we reviewed the daily schedules and determined the physician's office hours that day and took the midpoint. Medical records of each case for which we made such an estimate were reviewed by the principal investigator to ascertain accuracy of the estimates.
Similarly, time of symptom onset was based on the history taken during the first examination. When the note stated a specific time, we used that time. If the note indicated that symptoms began 3 days prior, we subtracted 3 days from the date and time of the examination. Specific times were assigned to times that were reported descriptively. For example, morning was coded as 8:00 am; middle of the night as 3:00 am, today as halfway between midnight and the time of examination.
To assess the changing risk of rupture with time, we used actuarial life table methods to obtain estimates of conditional risks.11 These allow assessment of the likelihood that a patient who has not been treated by designated times after symptoms will rupture within a specified period of time. Time was divided into intervals, initially of 24 hours, then 48 hours, and finally longer as the data became more sparse, and assumed a constant risk of rupture within the specified time intervals. We then estimated the probabilities that a patient who had not been treated by the beginning of each interval would rupture in the ensuing 24 hours, choosing this time period because, clinically, this seemed a reasonable time period to assume treatment would be initiated. The starting time was the onset of first symptoms and time of rupture was taken as the time of surgery at which the rupture was confirmed. Rupture was based on findings at surgery.
Physicians’ level of diagnostic certainty was determined by using the assessment portion of the initial physician "SOAP" (subjective, objective, assessment, plan) note. Patients for whom ectopic pregnancy was the first diagnosis were considered to have diagnostic certainty. All other diagnoses were considered "uncertain." Chi-square analyses, t tests, and Wilcoxon rank-sum tests were used for bivariate comparisons. We used logistic regression to assess the influence of the passage of time on rupture risk while controlling for other factors. We corrected odds ratios to approximate relative risks using the Zhang method of correction.12 Because symptom duration of more than 48 hours was associated with a lower risk of rupture, and at presentation, clinicians do not know which patient has experienced tubal rupture, characteristics of patients treated within or more than 48 hours are presented.
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RESULTS |
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The total time between onset of symptoms and treatment ranged from 3 hours to 1,593 hours (66 days) with a median of 172 hours (7 days). Table 1 shows the conditional probability of rupture, the risk that a patient who has not yet been treated by a specific time is likely to rupture in the ensuing day. These probabilities confirm that ruptures are most commonly found in women treated within 48 hours after onset of their symptoms. After this initial spike, the proportion with rupture drops and the risk of rupture remains relatively stable for the remaining time, but it does not disappear. Table 2 shows the average time that passed between a patient's onset of symptoms and seeing a physician (patient time), and time between her first examination for this episode of illness and treatment (system time). Once women have accessed care and seen a physician, those with rupture have shorter system times than those without rupture. Not surprisingly, women with ruptured tubal pregnancies were more likely than those with no rupture to have hemoperitoneum (96% versus 72%, respectively, P < .001) and higher amounts of estimated blood loss at surgery (500 mL versus 150 mL, respectively, P < .001). Length of stay was significantly longer among women with rupture (median 72 hours, range 24–288 hours) compared with women with no rupture (48 hours, range 24–360 hours; P < .001). Multivariable logistic regression (Table 3) shows that older age, having a shorter duration between symptom onset and treatment (
48 hours), and going to Hospital 2 were independently associated with tubal rupture. Clinical characteristics including level of ß-hCG, tubal mass size on ultrasound examination, the presence of tachycardia, rebound, pain, and vaginal bleeding were not independently associated with risk of tubal rupture.
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Table 4 presents descriptive characteristics of women with symptom duration of 48 hours or less and those with untreated symptoms for more than 48 hours because the former group had a higher rate of rupture. Women treated within 48 hours of their symptom onset were more likely to have prolonged times since their last period, to present to an emergency department for care, and to go to Hospital 2 for care. They were less likely to have vaginal bleeding but more likely to have guarding, rebound, and adnexal and cervical motion tenderness on physical examination. There was no significant difference between the groups in heart rate, ß-hCG level, or tubal mass size on ultrasound examination, nor in their physicians’ diagnostic certainty that the patient was experiencing an ectopic pregnancy. Patients for whom physicians were certain of the diagnosis experienced significantly shorter system times than patients about whom they were not certain (median time 9 hours [range 1–948 hours] versus 57 hours [range 2–826 hours]; P < .001, respectively).
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Women who obtained care at Hospital 2 compared with those who went to Hospital 1 had a significantly higher rupture rate (47% versus 23%; P < .001) and were also more likely to be treated within 48 hours of symptom onset (55% versus 45%; P = .01). These women tended to be African American (65% versus 35%; P < .001), were more likely to be uninsured (76% versus 9%; P < .001), and less likely to have vaginal bleeding (59% versus 74%; P < .05). They also had shorter times to treatment once they had accessed care (median [range]11 hours [1–780 hours] versus 50 hours [2–948 hours]; P > .001). There was no difference in the amount of patient time between women who sought care at Hospital 2 versus Hospital 1, nor was there a difference by hospital in physicians’ certainty of an ectopic diagnosis at the patient's first examination.
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DISCUSSION |
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We found, as others have, that factors important in diagnosing tubal pregnancy are not helpful in predicting risk of rupture.6–8 Time since last menstrual period, symptoms, physical findings, level of ß-hCG, and tubal mass size on ultrasound examination were not associated with rupture.
The 32% rupture rate in our study sample is higher than population-based rates,5 similar to other hospital-based rates,7,8 but lower than some reports in indigent populations.6 None of those studies found older age to be a risk factor for rupture. Yet, in our sample, increasing age is related to rupture. Whether this is a true relationship or one that is simply due to chance should be explored in future studies.
The finding that the hospital at which care was given is strongly associated with rupture requires closer scrutiny. The hospital may function as a proxy for measured and unmeasured factors. Measured factors that differed between the hospitals include race and insurance, characteristics that are often associated with worse health outcomes.13,14 Women at Hospital 2 were more likely to be African American, to be uninsured, and to have higher rupture rates. However, controlling for the hospital effects, neither race nor insurance is significantly associated with rupture. There was no difference between the hospitals in documentation of time. System time, the time between first examination and treatment, was shorter in Hospital 2 suggesting that it is not the characteristics of the hospital contributing to the higher rupture rate; rather, there is something different about the population of women who chose to go to that hospital. The hospital at which treatment is given is likely confounded by an unmeasured difference between the populations. For example, unmeasured factors such as patient perception of pain or access to care may affect time to care, may contribute to higher rupture rates, and may differ between the hospitals’ populations. Patients’ perceptions about and experiences getting care for tubal pregnancy should be further investigated.
Our study has 2 important strengths. First, data were obtained from patients’ initial examinations to ascertain detailed clinical data about symptoms, including onset times and physical examination and laboratory findings. Second, the importance of time between symptom onset and treatment on risk of rupture was assessed by calculating the likelihood of developing rupture with passing time. Other studies that report information about time do not track data back to a patient's initial encounter with the health care system for the episode of ectopic care, nor report the relationship of passing time with development of rupture.6–8 The sample of 221 patients is drawn from 2 teaching hospitals in New York City, one a municipal, and the other, a voluntary serving a more socioeconomically diverse population. This may limit the generalizability of our findings. Times are based on medical record documentation. Seventeen percent of the times were estimated and may not precisely reflect patients’ actual experiences of time. Our estimates of rupture risk may differ from those obtained by allowing the natural progression of all patients to rupture; however, there is no practicable way to observe the natural history of ectopic pregnancy.
Common sense would suggest that time between symptom onset and treatment would be an important risk factor for rupture, yet there are women who experienced nearly 2 months of symptoms and did not go on to rupture. This finding suggests that in some women the disease has a somewhat indolent course, but despite this there remained an ongoing and steady risk of rupture. Many of these women had accessed care and were being followed with serial ß-hCGs. The long duration of time to conclusive treatment experienced by some women may have been increased by the sequential delivery of methotrexate followed by surgical treatment. Women receiving both therapies had longer system and total times.
Despite advances in the diagnosis and treatment of tubal pregnancy, rupture remains a significant problem. There is a wide range in time between symptom onset and treatment. The risk of rupture is marked within 48 hours of symptom onset. Beyond that point, there is a reduction in risk of rupture that then levels with approximately a 2.5% risk of rupture in each ensuing 24 hour period of untreated symptoms. Unfortunately, classic signs, symptoms, diagnostic tests, and duration of symptoms are not helpful in predicting risk of rupture. Despite our finding of a group of women with prolonged symptoms and no rupture, the lack of effective means to predict rupture requires clinicians to be vigilant in treating tubal pregnancy. For the early-rupture group, there is likely little physicians can do to avert tubal rupture. For the remainder, the risk of rupture is always present regardless of duration of "chronicity" of symptomatology. Awareness of this persistent risk is even more crucial given the failure of current diagnostic tests to identify the subgroup of women with potential serious jeopardy from this treatable and correctable threat. Given the ongoing risk of rupture despite patient access of care, physicians should exercise caution when delaying treatment for tubal pregnancy.
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Footnotes |
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The authors thank Dr. Elizabeth Howell for clinical support, Ann Ruecker for programming help and Dr. Mark Chassin for constructive critiques on design and analysis. This project was support by grant R-01 B8509698 from AHRQ.
Received March 25, 2004. Received in revised form May 21, 2004. Accepted July 1, 2004.
10.1097/01.AOG.0000139912.65553.58
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REFERENCES |
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13. Committee on the Consequences of Uninsurance, Board on Health Care Services, Institute of Medicine. Coverage matters: insurance and healthcare. Washington, DC: National Academy Press; 2001.
14. Committee on Understanding and Eliminating Racial and Ethnic Disparities in Health Care, Institute of Medicine. Unequal treatment: confronting racial and ethnic disparities in health care. Smedley BD, Stith AY, Nelson AR, editors. Washington, DC: National Academy Press; 2003.
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