How to Interpret a Confidence Interval | Findings from Validation Visits for 2001 ART Data | Discrepancy Rates by Data Fields Selected for Validation How to Interpret a Confidence IntervalWhat is a
confidence interval? Why do we need to
consider confidence intervals if we already know the exact success rates
for each clinic in 2001? Why does the size
of the confidence interval vary for different clinics? Why should confidence intervals be considered when success rates from
different clinics are being compared? Even though one clinic’s success rate may appear higher than another’s based on the confidence intervals, these confidence intervals are only one indication that the success rate may be better. Other factors also must be considered when comparing rates from two clinics. For example, some clinics see more than the average number of patients with difficult infertility problems, while others discourage patients with a low probability of success. For further information see, important factors to consider when using the tables to assess a clinic. Findings from Validation Visits for 2001 ART DataClinic site visits for validation of 2001 ART data were conducted March through June 2003. During each visit, data reported by the clinic were compared with information recorded in patients’ charts. Records for 1,979 cycles at 40 clinics were randomly selected for validation. These selected cycles included 614 cycles that resulted in a pregnancy and 512 cycles that resulted in a live-birth delivery. Discrepancy rates are listed on the next page for key data items that were validated for each of the selected cycles. Most discrepancy rates were low (at or below 5%). Additionally, review of the discrepancies indicated that in the majority of cases, the error was minor and did not affect the success rates (see table below). In addition to fully validating data for the randomly selected 1,979 cycles, during each visit the validation team also reviewed the documentation for every live birth that had been reported to CDC. There were no cases found in which a live birth had been reported erroneously. In all, validation indicated that the data are being accurately reported by the clinics and that the success rates presented in this report are valid.
Discrepancy Rates by Data Fields Selected for Validation
|
Data Field Name | Discrepancy Rate |
Comments |
Patient age | 1.5% |
Nearly all discrepancies were within
1–2 years and did not result in a change in categorization of age
groups. |
Diagnosis of infertility | 5.8% | For many discrepancies, multiple causes of infertility had been diagnosed in the couple, but only a single cause had been recorded in the data set. |
Type of
ART (i.e., fresh vs. frozen; donor vs. nondonor) |
<1% | |
Use of ICSI | 1.0% |
|
Number of
embryos transferred |
1.7% |
Nearly all discrepancies involved
higher-order (>4) embryo transfers and were within 1–2 embryos. |
Outcome of ART treatment (i.e., pregnant vs. not pregnant) | <1% |
|
Number of
fetal hearts on ultrasound |
2.8% |
Of those with misreported number of
fetal hearts, only 6 cases (<1% of total) resulted in a change in
categorization of single- versus multiple-fetus pregnancy. |
Pregnancy
outcome (i.e., miscarriage, stillbirth, and live birth) |
<1% |
All discrepancies involved
misclassification between miscarriage and stillbirth. None of the
discrepancies involved misclassification of live birth. |
Number of infants born | <1% |
None of the discrepancies involved
misclassification of singleton- versus multiple-birth deliveries. |
Canceled cycles | <1% |
|
Notes: ART = assisted reproductive technology; ICSI = intracytoplasmic sperm injection. |
Selected Resources |
Implementation of the Fertility Clinic Success Rate and Certification Act of 1992
Assisted Reproductive Technology: Embryo Laboratory
Date last reviewed: 03/23/2006
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CDC/DRH 4770 Buford Hwy, NE MS K-20 Atlanta, GA 30341-3717 Phone number |
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