New clinical decision rule to exclude subarachnoid haemorrhage for acute headache: a prospective multicentre observational study

Systematic review identifies deficiencies in reporting of diagnostic test accuracy among clinical decision support systems

OBJECTIVES

This systematic review assesses the reporting quality and risk of bias in studies evaluating the diagnostic test accuracy (DTA) of clinical decision support systems (CDSS).

STUDY DESIGN AND SETTING

The Cochrane Library, PubMed/MEDLINE, Scopus, and Web of Science were searched for studies, published between January 1, 2016 and May 31, 2021, evaluating the DTA of CDSS for human patients. Articles using a patient's self-diagnosis, assessing disease severity, focusing on treatment/follow-up, or comparing pre-post CDSS implementation periods were excluded. All eligible studies were assessed for reporting quality using STARD 2015 and for risk of bias using QUADAS-2. Item ratings were presented using heat maps. This study was reported as per PRISMA-DTA.

RESULTS

In total, 158 of 2,820 screened articles were included in the analysis. The studies were heterogeneous in terms of study characteristics, reporting quality, risk of biases, and applicability concerns with few highly rated studies. Mostly the overall quality was deficient for items addressing the domains 'methodology,' 'results,' and 'other information'.

CONCLUSION

Our analysis revealed shortcomings in critical domains of reporting quality and risk of bias, indicating the need for additional guidance and training in an interdisciplinary scientific field with mixed biostatistical expertise.

Adding eosinophil count to EMERALD rules predicts subarachnoid haemorrhage better in emergency department

BACKGROUND

Subarachnoid haemorrhage (SAH) clinical decision rules can provide successful results in the differential diagnosis of non-traumatic headache.

AIM

The aim of this study is to investigate whether a laboratory parameter that can be added to clinical decision-making rules can better predict subarachnoid haemorrhages in patients presenting to the emergency department with headache.

METHODS

We conducted a retrospective cohort study between March 2017 and March 2019. Patients over the age of 18 who admitted to the emergency department with non-traumatic, acute headache last 14 days before admission and evaluated by imaging and laboratory studies were included in the study.

RESULTS

A total of 867 patients were included and 141 of them had SAH. In detecting the SAH, Ottawa SAH rule sensitivity (85.1%), specificity (47.1%), positive predictive value (PPV) (23.8%) and negative predictive value (NPV) (94.2%), and for EMERALD SAH, rule sensitivity (96.4%), specificity (43.2%), PPV (24.8%) and NPV (98.4%). In the regression analysis, statistically significant result was obtained to exclude the diagnosis of SAH with the decrease in the eosinophil value (cutoff < 0.085 10^3/µL, OR: 0.011, 95% CI: 0.001-0.213, p = 0.003). When eosinophil value was added to EMERALD SAH rule, it provided a 100% of sensitivity, a 38.4% of specificity, a 24% of PPV and a 100% of NPV in detecting the SAH.

CONCLUSIONS

EMERALD SAH rule plus eosinophil, which offers 100% sensitivity and NPV for predicting SAH in adult non-traumatic headaches, may be recommended as a successful and practical decision rule for clinical use according to the Ottawa and EMERALD SAH rule.

BET 1: The Ottawa Subarachnoid Hemorrhage Clinical Decision Rule shows high sensitivity but limited evidence of patient benefit

A short-cut review of the literature was carried out to examine the diagnostic test characteristics and potential patient benefits through the use of the Ottawa Subarachnoid Haemorrhage Clinical Decision Rule. Nine papers were identified as suitable for inclusion using the reported search strategy. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of the best papers are tabulated. It is concluded that the Ottawa Clinical Decision Rule has a high sensitivity for the diagnosis of subarachnoid haemorrhage; however, there is limited robust evidence of international generalisability and no evidence of improved patient outcomes following implementation. Further prospective research is required in populations with variable prevalence to evaluate the safety and effectiveness of this intervention, compared with routine evaluation strategies.

External validation for sensitivity of the Ottawa subarachnoid hemorrhage rule in a Japanese tertiary teaching hospital

The Ottawa subarachnoid hemorrhage (OSAH) rule is a validated clinical prediction rule for ruling out subarachnoid hemorrhage (SAH). Another SAH rule (Ottawa-like rule) was developed in Japan but was not well validated. We aimed to validate both rules by examining the sensitivity for ruling out SAH in Japanese patients diagnosed with SAH. We conducted a retrospective cohort study by reviewing the medical records of consecutive adult patients hospitalized with SAH at a tertiary-care teaching hospital in Japan who visited our emergency department between July 2009 and June 2019. Sensitivity and its 95% confidence interval (CI) were estimated for each rule for the diagnosis of SAH. In a total of 280 patients with SAH, 56 (20.0%) patients met the inclusion criteria and were analyzed for the OSAH rule, and a sensitivity of the OSAH rule was 56/56 (100%; 95% CI 93.6–100%). While, 126 (45%) patients met the inclusion criteria of the Ottawa-like rule, and the rule showed a sensitivity of 125/126 (99.2%; 95%CI 95.7–100%). The OSAH rule showed 100% sensitivity among our Japanese patients diagnosed with SAH. The implementation of the Ottawa-like rule should be cautious because the false-negative rate is up to 4%.

Subarachnoid haemorrhage rules in the decision for acute CT of the head: external validation in a UK cohort

BACKGROUND

The Ottawa subarachnoid haemorrhage (SAH) rule and the Emerald SAH rule are clinical decision tools to aid in the decision for computed tomography (CT) of the head in patients attending an emergency department (ED) with acute non-traumatic headache. The objective of this study was to analyse the performance of these rules in a contemporary UK cohort.

METHODS

We performed a retrospective external validation study. Patients undergoing CT of the head for the evaluation and treatment of non-traumatic headaches over a 6-month period in the ED at two tertiary centres were assessed. Each patient's Ottawa rule and Emerald rule were calculated and compared with their final diagnosis.

RESULTS

The cohort consisted of 366 patients and there were 16 cases of SAH (based on CT findings or the presence of xanthochromia in cerebrospinal fluid). The Ottawa rule identified 288 patients requiring CT of the head. The sensitivity of the Ottawa rule was 100% (95% confidence interval (CI) 71-100%) and the specificity was 22% (95% CI 18-27%). The Emerald rule identified 267 patients who required CT, and achieved a sensitivity of 81% (95% CI 54-96%) and a specificity of 27% (95% CI 23-32%).

CONCLUSIONS

The Ottawa SAH rule correctly identified all patients with SAH in this contemporary cohort. The Emerald rule did not perform as well in this cohort and is unsuitable for clinical use. The Ottawa rule is a useful tool to aid in the decision for CT of the head in patients presenting with acute non-traumatic headache to the ED.

Excluding subarachnoid haemorrhage within 24 hours: to LP or not to LP?

BACKGROUND AND PURPOSE

Subarachnoid haemorrhage (SAH) is a potentially life-threatening cause of acute headache. Current conventional practice in the United Kingdom (UK) is for head computed tomography (CT) followed by cerebrospinal fluid (CSF) xanthochromia analysis if the head CT is normal. However, with increasing radiological accuracy, head CT alone may be sufficient to exclude SAH without requiring CSF xanthochromia for confirmation. This study aims to determine whether CSF xanthochromia is still required to confirm exclusion of SAH after normal head CT within a tertiary referral centre.

METHODS

Data was obtained from Nottingham University Hospitals (NUH) NHS Trust databases on 999 patients presenting with symptoms suspicious of SAH from 2012 to 2015. All patients had CSF xanthochromia analysis when head CT was normal or inconclusive for suspected SAH.

RESULTS

A total of 179 patients were diagnosed with SAH (17.9%). 176 patients were diagnosed radiologically and 3 patients required further investigations. The 3 of the 802 patients who underwent lumbar puncture (LP) and were identified as having had SAH presented more than 24 hours after ictus. When stratified according to the time of presentation, a normal CT head was observed in those who presented within 24 hours from ictus (sensitivity of 100% [95% CI 92.5-100] and negative predictive value of 100% [97.2-100]).

CONCLUSION

Within a tertiary referral centre for SAH, a normal head CT has a very high negative predictive value to exclude SAH when carried out within 24 hours from ictus provided a 3rd generation CT scanner is utilised, and the scan is reported by a neuroradiologist. CSF xanthochromia analysis in this cohort may still be indicated in those presenting with a high clinical suspicion of SAH and in hospital settings where neuroradiologists or 3rd generation CT scanners are not easily accessible.

Subarachnoid Hemorrhage and Headache

PURPOSE FOR REVIEW

Subarachnoid hemorrhage is a serious and life-threatening medical condition which commonly presents with an acute headache. Unfortunately, it remains frequently misdiagnosed at initial presentation with dire consequences in terms of patient morbidity and mortality. The goal of this paper is to review salient features in the clinical history, as well as recently developed clinical decision rules, which can help determine which patients warrant further investigation for subarachnoid hemorrhage when the initial presentation is that of an acute headache.

RECENT FINDINGS

A recent prospective observational study showed that occipital location, stabbing quality, presence of meningism, and onset of headache during exertion were characteristics in the clinical history that can distinguish the headache of SAH from other causes. The Ottawa headache rule is a clinical decision tool which was developed to help identify patients presenting to the ED with acute non-traumatic headache who require investigation to rule out subarachnoid hemorrhage. Using this tool, it is recommended that patients who meet any one of the following 6 criteria are investigated further: Onset greater than or equal to 40 years, presence of neck pain or stiffness, witnessed loss of consciousness, onset during exertion, thunder clap headache (pain peaking within 1 s), or limited neck flexion on exam. An informed and thoughtful approach that takes into account the timing, presentation, risk factors, and resources, as discussed here, should help distinguish between the patient that warrants further evaluation and intervention for SAH and one who does not. The Ottawa SAH rule is a useful clinical decision tool for young inexperienced clinicians in order to avoid missed diagnoses. However, its clinical value is limited by its low specificity. Clinical decision tools with higher specificity are needed.