NIHR Signal Simple bedside check for nasogastric tube positioning is cost effective and prevents deaths

Published on 29 November 2016

In adults who need a nasogastric tube for a short time, pH testing was the best initial approach followed by X-ray confirmation if pH testing wasn’t successful. pH testing was four times less expensive than X-ray confirmation and when used in sequence both were cost effective uses of NHS resources.

Nasogastric tubes are used to deliver liquids directly to the stomach. Tubes can be misplaced, often into the lungs, with serious consequences, so their final position needs to be checked. This can be done in two ways. pH testing which detects whether the expected level of acidity is present, and X-rays. Death or lung damage that arises from misplaced nasogastric tube is avoidable and should never happen, something the NHS calls a “never event”.

Updated advice from the NHS in England restates the position that pH testing should remain the first choice to detect correct placement. This cost analysis supports the current approach of pH testing followed by X-ray if necessary.

It is important to consider the training of staff who carry out the test or read X-rays. A resource set to support providers is available from NHS improvement. Especially important if the harm from these events is to be reduced to zero.

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Why was this study needed?

Over 790,000 nasogastric tubes are used in the NHS each year. They are inserted through the nose and passed down to the stomach.

Healthcare professionals carrying out the procedure are unable to see exactly where the tube is going. The end of the tube may pass into the lungs which can cause serious harm, or even death, if liquids are then administered. Because of this, checks are recommended after the initial placement before the tube is used for any liquid.

During 2009/10, there were 41 never events reported in the NHS where a misplaced nasogastric or orogastric tube was not detected prior to use. As these should never happen, they are called “never events” and are monitored closely in the NHS. Detail in these monitoring reports suggest there are issues with x-ray interpretation at all times, and there may be increased risks from nasogastric placement or x-ray checking at night.

Because the procedure is still recognized as a cause of avoidable mortality and morbidity this author sought to study the cost and effectiveness trade-off between the two most commonly used methods as this has not been done previously.

What did this study do?

This cost utility analysis utilised three sources of evidence to populate a decision tree model. Effectiveness data was gathered from a systematic review and meta-analysis. Three studies were included on chest X-rays, three on pH testing and three on the probability of obtaining a sample for the pH test.

Quality of life patient outcomes were not covered in the literature, so were calculated by asking 23 adult surgical patients to rate the imagined impact of different nasogastric tube scenarios. These ranged from no complications to serious complications. Cost information was obtained from current NHS prices and staff costs.

The study was conducted with reference to healthcare in Scotland, but should be applicable to the rest of the UK.

What did it find?

  • If X-rays replaced pH testing completely as the first line test, this would cost £11,544 per quality adjusted life year (QALY).
  • The cost of all testing and staff costs associated with pH testing was £43.20 and for X-rays the equivalent was £158.64.
  • Compared with no checking, X-ray delivers a slightly higher QALY gain at 0.12 then pH testing at 0.11.
  • When the two scenarios were modelled the added value, or incremental cost effectiveness ratio, for pH testing was £392.73 per QALY, over a third lower than X-ray at £1,322. Both these ratios signify good value for the NHS.
  • The 23 people assessing the impact of nasogastric tube placement recorded a slight negative effect on health even for scenarios without complications. This rose in line with the severity of complications.

Sensitivity analyses indicate findings may be altered by tube aspiration success rates and X-ray interpretation errors.

What does current guidance say on this issue?

The National Patient Safety Agency reviewed incidents of misplaced nasogastric tubes in 2011 and reiterated the NICE 2006 guidance that nasogastric tubes should only be inserted if sufficiently experienced staff are available to check the position. Many cases of misplacement occur out of hours.

NICE recommends that correct placement be confirmed by aspiration and pH testing. If aspiration is not possible or the result is unclear, then X-ray is recommended. These steps should be repeated after any vomiting, retching, coughing or if the tube appears to have come out or there are new breathing problems. US, Canadian and European guidance suggests all patients should undergo x-ray confirmation.

Further detailed NHS guidance reiterating the initial nasogastric tube placement check was published in July 2016 and includes practical examples of how providers can implement and embed guidance in their organisations.

What are the implications?

The serious harms that can be caused by nasogastric tube misplacement are often avoidable and the cost of treating complications may be substantial. The findings from this study go some way to alleviating safety concerns by supporting existing NICE, NPSA and NHS recommendations.

If one of the 25 preventable events called “never events” in the NHS occur there is a financial penalty for the provider of £10,000 levied on top of the recovery of costs of care and procedures should a death occur.

Whilst pH testing may be the most cost effective and comparable to chest X-ray in terms of patient outcome, there remain some questions surrounding the correct interpretation of test results.  Ensuring healthcare professionals have adequate support and training should help minimise the risk of error regardless of the method of checking employed and might eventually reduce these “never events” to zero.

Citation and Funding

McFarland A. A cost utility analysis of the clinical algorithm for nasogastric tube placement confirmation in adult hospital patients. J Adv Nurs. 2016. [Epub ahead of print].

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Why was this study needed?

Over 790,000 nasogastric tubes are used in the NHS each year. They are inserted through the nose and passed down to the stomach.

Healthcare professionals carrying out the procedure are unable to see exactly where the tube is going. The end of the tube may pass into the lungs which can cause serious harm, or even death, if liquids are then administered. Because of this, checks are recommended after the initial placement before the tube is used for any liquid.

During 2009/10, there were 41 never events reported in the NHS where a misplaced nasogastric or orogastric tube was not detected prior to use. As these should never happen, they are called “never events” and are monitored closely in the NHS. Detail in these monitoring reports suggest there are issues with x-ray interpretation at all times, and there may be increased risks from nasogastric placement or x-ray checking at night.

Because the procedure is still recognized as a cause of avoidable mortality and morbidity this author sought to study the cost and effectiveness trade-off between the two most commonly used methods as this has not been done previously.

What did this study do?

This cost utility analysis utilised three sources of evidence to populate a decision tree model. Effectiveness data was gathered from a systematic review and meta-analysis. Three studies were included on chest X-rays, three on pH testing and three on the probability of obtaining a sample for the pH test.

Quality of life patient outcomes were not covered in the literature, so were calculated by asking 23 adult surgical patients to rate the imagined impact of different nasogastric tube scenarios. These ranged from no complications to serious complications. Cost information was obtained from current NHS prices and staff costs.

The study was conducted with reference to healthcare in Scotland, but should be applicable to the rest of the UK.

What did it find?

  • If X-rays replaced pH testing completely as the first line test, this would cost £11,544 per quality adjusted life year (QALY).
  • The cost of all testing and staff costs associated with pH testing was £43.20 and for X-rays the equivalent was £158.64.
  • Compared with no checking, X-ray delivers a slightly higher QALY gain at 0.12 then pH testing at 0.11.
  • When the two scenarios were modelled the added value, or incremental cost effectiveness ratio, for pH testing was £392.73 per QALY, over a third lower than X-ray at £1,322. Both these ratios signify good value for the NHS.
  • The 23 people assessing the impact of nasogastric tube placement recorded a slight negative effect on health even for scenarios without complications. This rose in line with the severity of complications.

Sensitivity analyses indicate findings may be altered by tube aspiration success rates and X-ray interpretation errors.

What does current guidance say on this issue?

The National Patient Safety Agency reviewed incidents of misplaced nasogastric tubes in 2011 and reiterated the NICE 2006 guidance that nasogastric tubes should only be inserted if sufficiently experienced staff are available to check the position. Many cases of misplacement occur out of hours.

NICE recommends that correct placement be confirmed by aspiration and pH testing. If aspiration is not possible or the result is unclear, then X-ray is recommended. These steps should be repeated after any vomiting, retching, coughing or if the tube appears to have come out or there are new breathing problems. US, Canadian and European guidance suggests all patients should undergo x-ray confirmation.

Further detailed NHS guidance reiterating the initial nasogastric tube placement check was published in July 2016 and includes practical examples of how providers can implement and embed guidance in their organisations.

What are the implications?

The serious harms that can be caused by nasogastric tube misplacement are often avoidable and the cost of treating complications may be substantial. The findings from this study go some way to alleviating safety concerns by supporting existing NICE, NPSA and NHS recommendations.

If one of the 25 preventable events called “never events” in the NHS occur there is a financial penalty for the provider of £10,000 levied on top of the recovery of costs of care and procedures should a death occur.

Whilst pH testing may be the most cost effective and comparable to chest X-ray in terms of patient outcome, there remain some questions surrounding the correct interpretation of test results.  Ensuring healthcare professionals have adequate support and training should help minimise the risk of error regardless of the method of checking employed and might eventually reduce these “never events” to zero.

Citation and Funding

McFarland A. A cost utility analysis of the clinical algorithm for nasogastric tube placement confirmation in adult hospital patients. J Adv Nurs. 2016. [Epub ahead of print].

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

A cost utility analysis of the clinical algorithm for nasogastric tube placement confirmation in adult hospital patients

Published on 12 August 2016

McFarland, A.

J Adv Nurs , 2016

AIM: To evaluate the effectiveness of pH paper testing of aspirate and chest x-ray for determining nasogastric tube (NGT) placement in terms of cost and patient outcome. BACKGROUND: Nasogastric tubes are frequently used in clinical practice, however during insertion the practitioner is blinded as to the precise final location. Despite robust checking procedures, recognised patient morbidity and mortality associated with this procedure have resulted in national safety alerts prompting the revision of all NGT care clinical guidelines. DESIGN: Cost utility analysis using economic modelling. METHODS: A decision tree was built and populated with effectiveness data gathered from a systematic search of the extant literature. Specificity, pooled sensitivity and event probabilities were calculated using statistical software. Patient outcome was measured in terms of quality of life. Health state utilities were gathered from a sample (n=23) of adult surgical patients using a recognised instrument. Cost data were gathered using published sources. The study adopted a third party payer perspective in a Scottish context and was completed in June 2013. RESULTS: The results confirm that the current UK algorithm advocated by the National Patient Safety Agency appears to offer the most cost effective approach to NGT confirmation in terms of cost and patient outcome. Sensitivity analyses indicate that these findings may be significantly altered by tube aspiration success and the rates of chest x-ray interpretation errors. CONCLUSION: The results confirm current UK recommendations and have wider policy implications for those areas whereby chest x-ray is recommended as the first and only acceptable confirmation approach. This article is protected by copyright. All rights reserved.

A quality adjusted life year (QALY) is a measure in which length of life is adjusted to reflect the quality of that life. One QALY is equal to one year of life in perfect health. QALYs are calculated by estimating the years of life remaining for a patient following a particular treatment or intervention and weighting each year with a quality-of-life score (on a 0 to 1 scale).

Incremental cost effectiveness ratio (ICER) demonstrates the difference in cost between two interventions, divided by the difference in their effect on outcomes. The calculation is based on cost and using an appropriate scale for the outcome of interest. The ICER then represents the average incremental cost associated with one additional unit of improvement on the chosen scale.

Expert commentary

This study confirms the cost utility of current guidance on nasogastric placement checks. But the clinical challenge is not the evidence base, but its implementation. A continuing feature of nasogastric ‘never events’ is X-ray misinterpretation by doctors who have never been taught to use the ‘four criteria’, or errors by nurses who have never received training on correct aspiration techniques and pH testing. Ensuring only staff who have the right competencies undertake these safety-critical checks is not only cost-effective, but can save patients, families and staff from the very real human costs of avoidable deaths and damaged respiratory systems.

Dr Frances Healey, Deputy Director of Patient Safety (Insight), NHS Improvement

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