Audit & Research

Discussion of Audit

1. METHODOLOGY OF AUDIT We have found that using the aforementioned methods within the already described system for audit, we were still unable to easily contact patients for outcomes of the pregnancy.

We have now created an additional system in recording the email address for each patient who visits the Practice, as well as all the nine points noted within the methodology above. However, there are difficulties even transcribing the email address correctly for a patient and even the patients themselves are giving us the wrong address or we are recording it incorrectly. To this end we have decided to send an email to each patient whilst they are attending the Practice, to ensure that the server has not returned the email to us as being undeliverable. The average time to sending an email to receiving the error message within our system is approximately 5 minutes. Should this happen, we can then still contact the patient while they are with us in the premises to further validate their email address.

We have already found this system to be very robust during 2007. We have been able to communicate with the patients who have had a high risk result but not elected to have any invasive testing to determine outcomes of the pregnancy to date.

In addition to this, we will use the email system which is available for 90% of our patients to automatically send outcome requests a month after the estimated date of confinement. Once the outcome for the patient is filled in within the Astraia database the reminders to the patient will cease.

Subsequent audits will hopefully show that this method not only decreases the time spent conducting audit by staff within MUMS, but also improves the overall outcome of patients.

To date we have only been able to account for 40% of pregnancy outcomes for all patients who have ever attended the Practice. However, for high-risk nuchal scans the outcome of the pregnancy is 100%.

2. PERFORMANACE OF THE SCREENING TEST Although the data for 2006 is incomplete, as at the time of compilation of this report on 27.04.07 we have had no extra cases of Downs Syndrome notified to us for 2006. The performance of the screening tests in detecting DS shows an improvement over the three years that MUMS has been in practice.

In 2004, we were mainly using the two hormones PAPP A and Beta HCG with the nuchal translucency measurement to achieve a 77% detection rate, that is a risk of 1:250 or worse at the time of the scan for a 6% false positive rate.

In 2005 we added the nasal bone data for absence or presence of the nasal bone into the calculation package and our detection rate increased to 87.5% with the false positive rate of 7%.

In 2006 we introduced tricuspid regurgitation in the later part of the year when all members of the company became accredited for incorporating this into the calculation package. Our detection rate since incorporating TR (though outcome data is incomplete for 2007) is currently running at 91% with only a 2.8% overall false positive rate. However, during this period of 2006 we changed our risk estimation to reflect the risk for DS at term and not at the actual gestational age at the time of when the scan was performed. The difference between the first trimester risk and term risk for DS is due to the prediction that nearly a third of all pregnancies affected with Downs syndrome will miscarry or result in stillbirth from the 13th week onwards. This would effectively reduce our false positive rate (FPR) by 30% ie from 6.7% in 2005 to 4.7 in 2006. However, the FPR has reduced to 3.1% overall for 2006 and further again in 2007 so far to 2.8%.

The age related bands we created for our audit are important for our practice as this now provides data on more specific age groups that we can provide for pre and post test counselling. Again, the fall in the FPR without compromising the detection rate for DS across the age groups is extremely encouraging and needs to be followed closely in future years. We hope that this is due to the increasing skills and experience of the team with the addition of TR into the calculation program.

The performance of the nasal bone data in improving the detection rate of Downs Syndrome has to be questioned as of the 9 cases of Downs Syndrome who were assigned low risk status, the nasal bone was present in seven and no comment was made in two cases. If we look at the data for 2005-2006 the nasal bone was thought to be present in 55% of cases of Downs Syndrome. This is a lot higher than the 33% that was reported by the original author Kypros Nicolaides for this finding. Thus our concern is that, had we removed the nasal bone data from our calculations, three of the low risk cases would have been re-classified as being high risk. We found like other investigators that we were more likely to say the nasal bone was absent when the nuchal translucency was greater than 3mm. There is a thought that in these cases of DS where the NB is thought to be present, there may only be one NB present and not the two normally found.

The action of the Practice to examine each case individually or accredited sonographers and doctors to determine whether this judgement on the presence of absence or absence of the nasal bone had occurred. The images held on record showed that we had correctly assigned the nasal bone status as present in the seven cases concerned. Thus, it would appear that our practise is correct but the performance of the nasal bone data is not as strong as the programme for calculating Downs Syndrome risks maybe unsupported.

Thus, we are now placing a much greater emphasis on the use of tricuspid regurgitation and our next audit report will hopefully show that the detection rate for Downs Syndrome is in excess of 90% due to the incorporation of this data whilst maintaining the false positive rate of less than 3%.

The negative aspect of using the TR within the calculation package does mean a longer scanning period and an increase in the return rate to achieve the measurement correctly. However, if as the audit perhaps alludes to, that incorporating TR into the calculation package reduces the screen positive rate without reducing the detection rate for DS, then this is worth the extra time for the concomitant reduction in invasive procedures.

There has been an update in 2007 of the calculation programme for Downs Syndrome to reflect the importance of tricuspid regurgitation, whilst reducing the role of the nasal bone in re-adjusting risks for Trisomy 21. This would be supported by our audit findings over the last three years.

In cases where DS was diagnosed antenatally, only 2 patients elected not to terminate the pregnancy. Both women when questioned were looking for reassurance that the pregnancy was normal. When their high risk status was identified they proceeded to an invasive test to prepare themselves for the birth of a baby with DS but not to proceed with TOP.

We also found that when the risk for DS was 1 in 2, only 1 patient had a normal outcome and this was due to the classification of the nasal bone. This is important information as some of the women within that group would not want to await further testing for DS or other chromosomal anomalies, especially if the issue of a medical rather than a surgical TOP is only available after 14 weeks of pregnancy.

In comparing our screening with that available to the NHS in the region there is a marked difference in the chances of having a high risk result returned after testing. Testing for Downs syndrome between 11 and 14 weeks is much safer for women as our test has a better ability to detect Downs syndrome as well as having a lot lower risk for having a high risk result but a normal pregnancy. This is very important to patients as you only want to have a test that is dependable and has a good chance of returning an acceptable risk for Downs syndrome.

In summary, though we yearn to be 100% correct in screening for DS within all the modalities of a screening test’s parameters but this is not feasible. However, we should not lower our sights from 100% and continue to learn from our experiences to achieve rates at least as good as the best published series to date. Currently, we are achieving this goal but will strive to maintain this through the process of audit and education for our company.