NIHR DC Discover

NIHR Signal A simple test can help point to serious illness in children

Published on 18 November 2015

doi: 10.3310/signal-000148

This review found that the capillary refill test was useful in diagnosing serious illness or dehydration in children. The quick test, done by pressing on the nail bed, is used to monitor blood flow. The review of studies testing its accuracy showed it can be used as a “red-flag” to identify (i.e.rule in) potential serious disease when present. The test’s low sensitivity means that a normal capillary refill time should not reassure clinicians that serious illness is absent (i.e.rule it out).

Children with prolonged capillary refill time were shown to have a four-fold risk of dying compared with children with normal capillary refill time. However, other clinical markers of risk were more useful for prediction: such as rapid breathing, a body temperature greater than 40°C, or warning signs of meningitis irritation (stiff neck, aversion to light, headache). The refill test is recommended in a range of guidelines, including those from NICE.

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Why was this study needed?

Infections remain the leading cause of death in children under five years. Feverish illness may be a sign of a serious infection but is a common and unspecific symptom. Between 20 and 40% of parents report feverish illness in their children each year, it is a common reason for a child to be taken to their GP and the second most common reason for a child being admitted to hospital.

There is some variation in how the test is performed, usually moderate pressure is applied to the nail of the thumb or the big toe until it goes white. The time taken until total recovery of the pink colour is the capillary refill time. A time of three seconds or more is usually considered abnormal. Future guidelines could provide specific instructions on how to perform and interpret the test.

The refill test is routinely used when assessing seriously ill or injured children, and is recommended in a range of guidelines, including NICE. However, there has never been a systematic review of the evidence of its diagnostic or prognostic use in seriously ill children.

What did this study do?

This was a systematic review of 24 studies with meta-analysis that measured capillary refill time and outcomes, including mortality, dehydration or serious illness in children aged up to 18 years of age. Thirteen studies were in high income countries and 11 in low or middle income countries. Studies had a minimum of 20 participants and were focussed on children without pre-existing heart or respiratory conditions; only one was in primary care.

Nine studies assessed the relationship between the refill test and mortality. Six studies looked at dehydration. The rest were on meningitis, sepsis, dengue fever, urinary tract infection, pneumonia and oxygen deficiency (hypoxia).

This was a robust systematic review. However, many of the included studies were poorly reported, for example, not recording where on the body the test was performed.

What did it find?

  • A child with prolonged refill time had a 4-fold greater risk of dying compared to a child with normal refill time (positive likelihood ratio 4.49, 95% confidence interval [CI] 3.06 to 6.57). However, sensitivity was low, around 35%. This result was from a meta-analysis of nine studies, eight of which were in low or middle income countries.
  • Prolonged refill time in children attending emergency departments with vomiting and diarrhoea helped in the diagnosis of significant dehydration (positive likelihood ratios ranged from 1.3 to 16.9). Again, a normal refill time was not helpful in ruling out dehydration. Most studies looking at dehydration were in high income countries. Meta-analysis wasn’t possible because of large differences between studies.
  • Prolonged refill time was found to be a marker of increased risk for many other outcomes, including meningitis, sepsis, admission to hospital, hypoxia, severity of illness and dengue fever.

What does current guidance say on this issue?

The capillary refill test is included as part of the routine or initial assessment of seriously ill or injured children in a number of child-focussed NICE guidelines, including those on feverish illness, diarrhoea and vomiting, and bacterial meningitis and meningococcal septicaemia. Prolonged refill time is set at a threshold of three or more seconds.

Capillary refill time is also recommended in guidelines on advanced paediatric life support, severe sepsis or septic shock in children, including those published by the Surviving Sepsis Campaign.

What are the implications?

The results show that prolonged capillary refill time can be used as a “red-flag” to indicate that the child has a serious illness or dehydration. However, the low sensitivity of the test means that normal refill times do not rule out serious illness or dehydration. The capillary refill test is better for ruling in possible serious illness, than ruling out a cause for concern.

Refill time is also a good prognostic tool, to predict poor outcomes. However refill time was found to be less useful as a marker of risk than some other clinical signs, such as rapid breathing, a body temperature greater than 40°C, or signs of meningeal irritation, such as a stiff neck, aversion to light, and headache.

The authors suggest that future guidelines recommending the capillary refill test should clearly describe the method (including where and for how long to press, and whether to use a stopwatch) as well as its interpretation (including providing whole-second cut off values).

Bibliography

Dellinger RP, Levy MM, Rhodes A, et al. Surviving Sepsis Campaign: International Guidelines for Management of Severe Sepsis and Septic Shock, 2012. Intens Care Med. 2013; 39(2):165–228.

NICE. Bacterial meningitis and meningococcal septicaemia: Management of bacterial meningitis and meningococcal septicaemia in children and young people younger than 16 years in primary and secondary care. CG102. London: National Institute for Health and Care Excellence; 2010.

NICE. Diarrhoea and vomiting in children: Diarrhoea and vomiting caused by gastroenteritis: diagnosis, assessment and management in children younger than 5 years. CG84. London: National Institute for Health and Care Excellence; 2009.

NICE. Feverish illness in children: Assessment and initial management in children younger than 5 years. CG160. London: National Institute for Health and Care Excellence; 2013.

The NNT. Diagnostics and Likelihood Ratios. The NNT Group; 2015.

Why was this study needed?

Infections remain the leading cause of death in children under five years. Feverish illness may be a sign of a serious infection but is a common and unspecific symptom. Between 20 and 40% of parents report feverish illness in their children each year, it is a common reason for a child to be taken to their GP and the second most common reason for a child being admitted to hospital.

There is some variation in how the test is performed, usually moderate pressure is applied to the nail of the thumb or the big toe until it goes white. The time taken until total recovery of the pink colour is the capillary refill time. A time of three seconds or more is usually considered abnormal. Future guidelines could provide specific instructions on how to perform and interpret the test.

The refill test is routinely used when assessing seriously ill or injured children, and is recommended in a range of guidelines, including NICE. However, there has never been a systematic review of the evidence of its diagnostic or prognostic use in seriously ill children.

What did this study do?

This was a systematic review of 24 studies with meta-analysis that measured capillary refill time and outcomes, including mortality, dehydration or serious illness in children aged up to 18 years of age. Thirteen studies were in high income countries and 11 in low or middle income countries. Studies had a minimum of 20 participants and were focussed on children without pre-existing heart or respiratory conditions; only one was in primary care.

Nine studies assessed the relationship between the refill test and mortality. Six studies looked at dehydration. The rest were on meningitis, sepsis, dengue fever, urinary tract infection, pneumonia and oxygen deficiency (hypoxia).

This was a robust systematic review. However, many of the included studies were poorly reported, for example, not recording where on the body the test was performed.

What did it find?

  • A child with prolonged refill time had a 4-fold greater risk of dying compared to a child with normal refill time (positive likelihood ratio 4.49, 95% confidence interval [CI] 3.06 to 6.57). However, sensitivity was low, around 35%. This result was from a meta-analysis of nine studies, eight of which were in low or middle income countries.
  • Prolonged refill time in children attending emergency departments with vomiting and diarrhoea helped in the diagnosis of significant dehydration (positive likelihood ratios ranged from 1.3 to 16.9). Again, a normal refill time was not helpful in ruling out dehydration. Most studies looking at dehydration were in high income countries. Meta-analysis wasn’t possible because of large differences between studies.
  • Prolonged refill time was found to be a marker of increased risk for many other outcomes, including meningitis, sepsis, admission to hospital, hypoxia, severity of illness and dengue fever.

What does current guidance say on this issue?

The capillary refill test is included as part of the routine or initial assessment of seriously ill or injured children in a number of child-focussed NICE guidelines, including those on feverish illness, diarrhoea and vomiting, and bacterial meningitis and meningococcal septicaemia. Prolonged refill time is set at a threshold of three or more seconds.

Capillary refill time is also recommended in guidelines on advanced paediatric life support, severe sepsis or septic shock in children, including those published by the Surviving Sepsis Campaign.

What are the implications?

The results show that prolonged capillary refill time can be used as a “red-flag” to indicate that the child has a serious illness or dehydration. However, the low sensitivity of the test means that normal refill times do not rule out serious illness or dehydration. The capillary refill test is better for ruling in possible serious illness, than ruling out a cause for concern.

Refill time is also a good prognostic tool, to predict poor outcomes. However refill time was found to be less useful as a marker of risk than some other clinical signs, such as rapid breathing, a body temperature greater than 40°C, or signs of meningeal irritation, such as a stiff neck, aversion to light, and headache.

The authors suggest that future guidelines recommending the capillary refill test should clearly describe the method (including where and for how long to press, and whether to use a stopwatch) as well as its interpretation (including providing whole-second cut off values).

Bibliography

Dellinger RP, Levy MM, Rhodes A, et al. Surviving Sepsis Campaign: International Guidelines for Management of Severe Sepsis and Septic Shock, 2012. Intens Care Med. 2013; 39(2):165–228.

NICE. Bacterial meningitis and meningococcal septicaemia: Management of bacterial meningitis and meningococcal septicaemia in children and young people younger than 16 years in primary and secondary care. CG102. London: National Institute for Health and Care Excellence; 2010.

NICE. Diarrhoea and vomiting in children: Diarrhoea and vomiting caused by gastroenteritis: diagnosis, assessment and management in children younger than 5 years. CG84. London: National Institute for Health and Care Excellence; 2009.

NICE. Feverish illness in children: Assessment and initial management in children younger than 5 years. CG160. London: National Institute for Health and Care Excellence; 2013.

The NNT. Diagnostics and Likelihood Ratios. The NNT Group; 2015.

The Diagnostic Value of Capillary Refill Time for Detecting Serious Illness in Children: A Systematic Review and Meta-Analysis

Published on 17 September 2015

Fleming, S.,Gill, P.,Jones, C.,Taylor, J. A.,Van den Bruel, A.,Heneghan, C.,Roberts, N.,Thompson, M.

PLoS One Volume 10 , 2015

IMPORTANCE: Capillary refill time (CRT) is widely recommended as part of the routine assessment of unwell children. OBJECTIVE: To determine the diagnostic value of capillary refill time for a range of serious outcomes in children. METHODS: We searched Medline, Embase and CINAHL from inception to June 2014. We included studies that measured both capillary refill time and a relevant clinical outcome such as mortality, dehydration, meningitis, or other serious illnesses in children aged up to 18 years of age. We screened 1,265 references, of which 24 papers were included in this review. Where sufficient studies were available, we conducted meta-analysis and constructed hierarchical summary ROC curves. RESULTS: Meta-analysis on the relationship between capillary refill time and mortality resulted in sensitivity of 34.6% (95% CI 23.9 to 47.1%), specificity 92.3% (88.6 to 94.8%), positive likelihood ratio 4.49 (3.06 to 6.57), and negative likelihood ratio 0.71 (0.60 to 0.84). Studies of children attending Emergency Departments with vomiting and diarrhea showed that capillary refill time had specificity of 89 to 94% for identifying 5% dehydration, but sensitivity ranged from 0 to 94%. This level of heterogeneity precluded formal meta-analysis of this outcome. Meta-analysis was not possible for other outcomes due to insufficient data, but we found consistently high specificity for a range of outcomes including meningitis, sepsis, admission to hospital, hypoxia, severity of illness and dengue. CONCLUSIONS: Our results show that capillary refill time is a specific sign, indicating that it can be used as a "red-flag": children with prolonged capillary refill time have a four-fold risk of dying compared to children with normal capillary refill time. The low sensitivity means that a normal capillary refill time should not reassure clinicians.

Likelihood ratios are the ratio of the probability that a test result is correct to the probability that a test result is incorrect. Ratios are always calculated for both positive and negative test results, using the following formula:

Positive likelihood ratio = sensitivity / 1- specificity

Negative likelihood ratio = 1- sensitivity / specificity

Sensitivity is the proportion of people with a disease who are correctly identified as having that disease by the diagnostic test. For example, if a test has a sensitivity of 90%, this means that it correctly identified 90% of the people with the disease, but missed 10% (these people were ‘false negatives’ on the test).

Specificity is the proportion of people without a disease who are correctly identified as not having that disease by the diagnostic test. For example, if a test has a specificity of 95%, this means that it correctly identified 95% of the people who did not have the disease, but that 5% of people without the disease were incorrectly diagnosed as having the disease (these people were ‘false positives’ on the test).

Expert commentary

This strength of this review – of covering multiple clinical scenarios from different settings – is also its weakness. So, an abnormal refill time is reliably associated with mortality, with several infections and with the need (or not) for hospital admission. However, the test was not sufficiently accurate to allow the clinician to use a negative test to avoid action. This reduces its clinical worth considerably: ‘rule-out’ tests are much more useful than ‘rule in’ ones. Furthermore, this study – and most of the underlying papers – reports the utility of the test in a vacuum, whereas the clinical reality is that there are many other factors available to help the clinician in deciding upon a course of action. It would be rare indeed for a clinician to have refill time and nothing else upon which to decide. So, refill time works, but only as part of a comprehensive assessment.

Willie Hamilton, Professor of Primary Care Diagnostics, University of Exeter Medical School