Research into practice: acutely ill children

CLINICAL FEATURES

Symptoms and signs are the first and often only information available to support clinical decision making in primary care. Despite their central role, evidence on their value in primary care settings is surprisingly scarce. Of the 30 diagnostic studies on clinical features for serious infection in children identified in a systematic review, only a single study (of 4000 children in Belgium) was performed in primary care.² Given that initial assessment of children also occurs over the telephone, there is also very little research on how accurate such triage is.

Parental concern that the illness is different is a powerful predictor of serious infections: parental concern is 14 times more likely in children with a serious infection.³ Yet, in describing children’s symptoms and severity, something seems to get ‘lost in translation’; for example, a study found that parental report of breathing difficulty was poorly predictive of later diagnosis of serious respiratory infection, and did not correlate with triage nurse findings.⁴

Some clinical features have been shown to be ‘red flags’, that is, they raise the likelihood of a serious infection when present. When a child presents in primary care with a temperature of 40°C, the likelihood of a serious infection increases substantially from <1% to 5%.³ In addition, classic textbook signs such as cyanosis, poor peripheral circulation, rapid breathing, crackles on auscultation, diminished breath sounds, meningeal irritation, petechial rash, and decreased consciousness are all important red flags for serious infections. The National Institute for Health and Care Excellence (NICE) has incorporated many of these ‘red flag’ features into their traffic light system for assessing febrile children <5 years of age.⁵

However, no single clinical feature seems to have ‘rule out’ value, such that the absence of that feature makes a serious infection less likely. Combinations of clinical features may be slightly better at ruling out serious infection. Only one such clinical prediction rule has been developed in primary care, and can largely rule out serious infections when each of the following features are negative: clinician gut feeling, dyspnoea, temperature >39.5°C, and diarrhoea in a child aged 1–2.5 years. This clinical prediction rule has a sensitivity of 97% and a specificity of 87%.³ Or rather, when the prediction rule is negative (none of the features are present), the likelihood of a serious infection decreases from 1% to 0%; conversely when at least one feature is present, the likelihood of a serious infection increases to 6%. Other combinations or prediction rules are inferior to this.⁶

HEART AND BREATHING RATE

Children with confirmed serious infections in secondary care settings typically have faster heart rates and breathing rates. Indeed, NICE recommends measuring heart and breathing rate in each feverish child⁵ and cites age-dependent cut-offs for tachycardia and tachypnoea. However, a recent systematic review collating all available evidence on normal ranges for heart and breathing rate questioned these thresholds of ‘what constitutes a normal value’.¹² For example, a heart rate of 140 beats/min in a 5-year old child as recommended by NICE as the cut-off for tachycardia is well above the 99th percentile, (99th percentile = 131 beats/min) suggesting that the NICE cut-off might lead to misclassifying tachycardic children as normal. Conversely, a breathing rate of 50 breaths/min in a child aged 6 months corresponds with the 75th percentile, suggesting that an overly large proportion of normal children would be wrongly classified as tachypnoeic. This is even more important in feverish children as research indicates that heart rate increases by about 10 beats/min¹³ and breathing rates by 2 breaths/min¹⁴ for every increase in body temperature with 1°C.

GUT FEELING

A clinician’s feeling that ‘something is wrong’, also referred to as a gut feeling, has been found to be a specific marker of serious infection.³ Whenever this feeling is present, the likelihood of a serious infection increases 10-fold, from <1% to 11% in a primary care setting. Its diagnostic value is consistent in children of all ages and is independent of the child’s specific diagnosis or presence of fever.¹⁵ Gut feeling is also a stronger red flag than clinical impression, probably because gut feeling is triggered not only by clinical features but also by contextual factors such as parental concern that the illness is different from previous illnesses. Especially in primary care where GPs may have a longstanding relation with their patients, such extra-clinical information provides doctors with an additional diagnostic tool.

BLOOD TESTS

In primary care, blood tests play only a marginal role in the diagnostic process of acutely ill children, mostly because decisions need to be taken before the result comes back from the laboratory. Point-of-care tests allow results to become available within the timeframe of a single consultation, making them potentially useful for referral decisions or antibiotic prescribing.

Limited evidence on the value of laboratory tests in the ambulatory setting is available, none of which was obtained in primary care. Nonetheless, the evidence does suggest that CRP and procalcitonin provide the most diagnostic value, with CRP levels <20 mg/L and procalcitonin levels <0.5 ng/mL ruling out serious infections.¹⁶

SAFETY NETTING

The dynamic nature of infections emerging over hours or days with a varying constellation of symptoms means that some children with a serious infection will not be identified at first contact. This is especially important in children presenting early in the course of illness at which point no specific signs may have developed. Safety netting is an integral part of the diagnostic process, to deal with residual uncertainty when either the diagnosis is uncertain, complications of a certain diagnosis may occur, or the patient is at higher risk for developing complications.¹⁷ GPs often provide advice on which symptoms parents should look for, where to go for further help, and expected illness trajectory.¹⁸

But, we don’t know whether verbal advice, or patient leaflets, or new forms of communication or social media have the most impact, and what parents would find most useful.

CONCLUSION

The assessment of acutely ill children in primary care should focus on identifying children who can be safely managed in the community, and research in this area is catching up with what GPs need to inform their practice. Diagnostic tests can assist in this process in two ways: either a test is a useful red flag making a serious infection more likely when present (but not making it less likely when absent), or a test is able to rule out a serious infection when negative. Clinical features with high red flag value include classic signs such as neck stiffness or increased breathing rate. Ruling out serious infections requires a combination of clinical features. Laboratory tests such as CRP may be potentially useful but primary care evidence in children is currently lacking.

Although children are getting healthier, acute infections will remain common (although largely not serious) leading parents to inevitably worry about their child, and this perennial concern drives much of the continuing rise in attendances and admissions. The research that is needed now to further inform parents, NHS telephone advice, triage, and face to-face assessment needs to be based in primary care, and evaluate clinical features, laboratory tests, and safety netting, taking into account other diagnostic information such as contextual factors.