Guideline Recommendations for Management of Aneurysmal Subarachnoid Hemorrhage

Emergency Treatment and Initial Management

Patients with aneurysmal subarachnoid hemorrhage should receive immediate emergency care that includes early aneurysm obliteration (ideally within 24 hours when feasible), admission to a specialized neurocritical care unit, and oral nimodipine 60 mg every 4 hours for 21 days. 1
Blood pressure should be controlled with short‑acting, titratable agents to minimize re‑bleeding while preserving cerebral perfusion. 2
In severely hypertensive patients (systolic > 180–200 mmHg), blood pressure should be gradually reduced, but hypotension must be avoided (maintain MAP ≥ 65 mmHg). 2

Pharmacotherapy

For patients who cannot swallow, nimodipine may be administered via enteral tube (≈ 80 mg daily) or rectal suppository (≈ 325 mg daily). 3
Aspirin and other antiplatelet agents should be withheld until after the aneurysm has been secured. 3

Timing of Aneurysm Securing

Secure the ruptured aneurysm as early as possible (ideally ≤ 24 hours); early treatment reduces re‑bleeding risk and improves outcomes compared with delayed treatment (> 24 hours). 1

Selection of Treatment Modality

Anterior circulation aneurysms that are suitable for both techniques: primary endovascular coiling is preferred over surgical clipping to achieve better 1‑year functional outcomes. 2
Posterior circulation aneurysms: endovascular coiling is strongly favored (relative risk 0.41 for death or dependency) compared with clipping. [2] [4]
Patients with large intraparenchymal hematoma and depressed consciousness: emergency surgical clot evacuation combined with aneurysm clipping markedly lowers mortality (≈ 27 % vs ≈ 80 % with conservative care). [2] [4]
Wide‑neck aneurysms not amenable to primary coiling or clipping: stent‑assisted coiling or flow‑diverter devices are reasonable options. 2
Ruptured saccular aneurysms that can be treated with primary coiling or clipping: avoid stents or flow diverters because they increase complication rates. [1] [2]

Treatment Goals

Aim for complete aneurysm obliteration whenever technically feasible; incomplete obliteration significantly raises the risk of re‑bleeding and need for retreatment. 1
If complete obliteration is not possible, partial treatment that secures the rupture site is acceptable, with planned retreatment within 1–3 months. 2

Fluid and Hemodynamic Management

Maintain euvolemia; prophylactic hypervolemia does not improve outcomes and may cause harm. 5

Avoidance of Harmful Practices (Pitfalls)

Do not delay aneurysm treatment beyond 24 hours when feasible, as early re‑bleeding carries high mortality. [1] [4]
Do not employ prophylactic hypervolemia (“triple‑H” therapy), which lacks supporting evidence and may be detrimental. 5
Do not use stents or flow diverters for ruptured saccular aneurysms amenable to primary coiling or clipping due to higher complication risk. [1] [2]
Do not allow hypotension (MAP < 65 mmHg) during blood‑pressure management, as it compromises cerebral perfusion. 2

Management of Subarachnoid Hemorrhage

Diagnostic Approach

The American College of Neurology recommends obtaining an immediate noncontrast head CT for patients with suspected subarachnoid hemorrhage, and if negative but clinical suspicion remains high, proceed directly to lumbar puncture looking for xanthochromia and elevated bilirubin 6
CT sensitivity is time-dependent, with 98-100% sensitivity within 12 hours, declining to 93% at 24 hours and 57-85% by day 6, making early imaging critical 6
Misdiagnosis occurs in up to 12% of cases, so maintain high clinical suspicion for acute severe headache 6

Initial Severity Assessment

Rapidly grade clinical severity using Hunt and Hess or World Federation of Neurological Surgeons scales, which is the single most useful predictor of outcome 6
Transfer immediately to a high-volume center with neurosurgeons, neuroendovascular specialists, and neurointensivists 7

Blood Pressure Management

Control blood pressure with short-acting titratable agents, avoiding both severe hypertension and hypotension until the aneurysm is secured 6, 8
Gradual BP reduction is necessary when severely hypertensive, but hypotension must be strictly avoided as it worsens cerebral perfusion 8

Aneurysm Obliteration

Secure the ruptured aneurysm as early as feasible, which is the only proven method to reduce rebleeding risk and must not be delayed 8
For anterior circulation aneurysms amenable to both techniques, endovascular coiling is preferred over surgical clipping to improve 1-year functional outcomes 6, 7

Acute Hydrocephalus Management

Perform urgent CSF diversion via external ventricular drainage or lumbar drainage if acute symptomatic hydrocephalus develops 6, 7

Neurocritical Care Unit Management

Admit to a specialized neurocritical care unit with evidence-based protocols and frequent neurological assessments 7
Maintain euvolemia, not hypervolemia, as prophylactic hypervolemia has not improved outcomes and may be harmful 7

Delayed Cerebral Ischemia Management

If delayed cerebral ischemia develops, induce hypertension while maintaining euvolemia unless baseline BP is already elevated or cardiac status precludes it 6, 7
Elevating blood pressure while maintaining euvolemia benefits patients with symptomatic DCI 7

Additional Supportive Care

Initiate venous thromboembolism prophylaxis once the aneurysm is secured 7
Use standardized ICU care bundles for mechanical ventilation when required 7
Emergency reversal of anticoagulants if patient is anticoagulated 7

Long-term Rehabilitation

Implement multidisciplinary team approach to identify discharge needs and design rehabilitation 7
Use validated screening tools for physical, cognitive, and behavioral deficits 7
Provide interventions for mood disorders to improve long-term outcomes 7

Acute Management of Subarachnoid Hemorrhage

Immediate Diagnostic Workup

Airway and Initial Neurological Assessment

Blood Pressure Management

Nimodipine Therapy

Aneurysm Securing

Management of Acute Hydrocephalus

Diagnostic Accuracy and Missed Cases

Acute Subarachnoid Hemorrhage: Evidence‑Based Management Guidelines

Blood‑Pressure Management

Target systolic blood pressure 160–180 mmHg (gradual reduction) while maintaining mean arterial pressure ≥65 mmHg using short‑acting, titratable intravenous agents (e.g., nicardipine or labetalol). This balances the risk of re‑bleeding against cerebral perfusion and avoids hypotension‑induced ischemia. 14 15
Avoid sudden, profound drops in blood pressure, as they may precipitate cerebral ischemia. 14
Meta‑analysis evidence suggests higher re‑bleeding rates when systolic pressure exceeds 160 mmHg, although the optimal target remains uncertain. 14

Early Aneurysm Securing

Secure the ruptured aneurysm as early as feasible, ideally within 24 hours of onset, to markedly reduce catastrophic re‑bleeding (mortality 70–80 %). 14
Re‑bleeding risk is greatest in the first 2–12 hours, with 4–13.6 % occurring within 24 hours and > 33 % within the first 3 hours. 15

Choice of Definitive Treatment

Anterior‑circulation aneurysms

Primary endovascular coiling is preferred over surgical clipping because it yields superior 1‑year functional outcomes. 14

Posterior‑circulation aneurysms

Endovascular coiling is strongly favored; it reduces the risk of death or dependency (relative risk 0.41 versus clipping). 14

Large intraparenchymal hematoma with depressed consciousness

Emergency surgical clot evacuation combined with aneurysm clipping reduces mortality (~27 % vs ≈ 80 % with conservative care). 14

Wide‑neck aneurysms not amenable to primary coiling or clipping

Stent‑assisted coiling or flow‑diverter devices are reasonable alternatives. 14
Conversely, for ruptured saccular aneurysms that can be treated with primary coiling or clipping, the use of stents or flow diverters should be avoided because they increase complication rates without added benefit. 14

Antifibrinolytic Therapy

Short‑term antifibrinolytic therapy (< 72 h) with tranexamic acid or aminocaproic acid may be considered only when aneurysm obliteration is unavoidably delayed, the patient has a high re‑bleeding risk, and no contraindications exist. 15
The 2023 ULTRA trial showed that tranexamic acid does not significantly lower re‑bleeding rates nor improve functional outcomes when aneurysms are secured early. 14
Antifibrinolytics are associated with an increased risk of deep‑vein thrombosis (no increase in pulmonary embolism). 15
Neither tranexamic acid nor aminocaproic acid is FDA‑approved for use in acute subarachnoid hemorrhage. 15

Anticoagulation Reversal

In patients on anticoagulants, emergent reversal should be performed based on clinical judgment, despite the lack of formal studies in SAH cohorts. 14

Multidisciplinary Evaluation & Systems of Care

Treatment modality (coiling vs clipping) should be decided by a multidisciplinary team comprising cerebrovascular neurosurgeons, endovascular specialists, and neurointensivists. 14
Patients should be transferred promptly to a high‑volume center (≥ 35 SAH cases per year) equipped with neurosurgery, endovascular, and neurocritical‑care expertise. 14

Guideline Recommendations for Management of Aneurysmal Subarachnoid Hemorrhage

Diagnosis and Vascular Imaging

Perform digital subtraction angiography with 3‑dimensional rotational angiography immediately after SAH confirmation to delineate the aneurysm and guide definitive treatment – AHA/ASA guideline (Class I, Level B) 16

Clinical Severity Assessment

Use the Hunt‑Hess or World Federation of Neurological Surgeons (WFNS) scales on presentation; the initial grade is the most powerful predictor of functional outcome – AHA/ASA recommendation (strong) 16

Blood‑Pressure Management Prior to Aneurysm Securement

Target systolic blood pressure < 160 mm Hg while maintaining mean arterial pressure ≥ 65 mm Hg using short‑acting titratable IV agents (e.g., nicardipine, labetalol); avoid both severe hypertension and hypotension – AHA/ASA (strong) 16
Never permit MAP < 65 mm Hg, as cerebral hypoperfusion worsens outcomes – AHA/ASA (strong) 16

Timing and Modality of Aneurysm Securement

Early Securing

Secure the ruptured aneurysm as early as feasible, ideally within 24 h, because early treatment is the only proven strategy to reduce catastrophic re‑bleeding (mortality 70‑80 % without treatment) – AHA/ASA (strong) 16

Endovascular vs. Surgical Choice

For anterior‑circulation aneurysms amenable to both techniques, endovascular coiling is preferred over surgical clipping to achieve superior 1‑year functional outcomes – AHA/ASA (Class I, Level A) 17
For posterior‑circulation aneurysms, endovascular coiling is strongly favored, conferring a relative risk of 0.41 for death or dependency compared with clipping – AHA/ASA (Class I, Level A) 17
In patients with a large intraparenchymal hematoma (> ≈ 50 cm³) who retain spontaneous respiration and pain response, emergent surgical clot evacuation combined with aneurysm clipping reduces mortality from ~ 80 % to ~ 27 % – AHA/ASA (Class I, Level B) 17

Technical Considerations

Aim for complete aneurysm obliteration whenever technically possible – AHA/ASA (strong) 16
Avoid stent‑assisted coiling or flow‑diverter placement in the acute phase because they require dual antiplatelet therapy and increase the risk of hemorrhagic complications (e.g., ventriculostomy‑related bleed) – AHA/ASA (strong) 17

Multidisciplinary Decision‑Making

Treatment decisions should involve both experienced endovascular and microsurgical specialists, either individually or as a collaborative team – AHA/ASA (strong) 17

Pharmacologic Neuroprotection

Nimodipine

Administer oral nimodipine 60 mg every 4 h for 21 days, initiated as soon as possible within 96 h of hemorrhage onset – AHA/ASA (Class I, Level A) [16][18]
Nimodipine improves neurological outcomes but does not prevent angiographic vasospasm – AHA/ASA (moderate evidence) [16][18]

Transfer to High‑Volume Centers

Immediately transfer patients to centers treating > 35 SAH cases per year and staffed with dedicated cerebrovascular surgeons, endovascular experts, and neurocritical‑care teams – AHA/ASA (strong) 16

Management of Acute Hydrocephalus

Treat symptomatic acute hydrocephalus urgently with cerebrospinal‑fluid diversion (external ventricular drain or lumbar drain) tailored to the clinical scenario – AHA/ASA (Class I, Level B) [16][18]

Prevention and Treatment of Delayed Cerebral Ischemia (DCI)

Prophylaxis

Maintain euvolemia and normal circulating blood volume; avoid prophylactic hypervolemia and routine “triple‑H” therapy – AHA/ASA (Class I, Level B) 16

Symptomatic DCI

Induce hypertension while preserving euvolemia for patients with symptomatic DCI, unless baseline blood pressure is already elevated or cardiac status precludes it – AHA/ASA (Class I, Level B) [16][18]
Consider cerebral angioplasty and/or selective intra‑arterial vasodilator therapy as adjuncts or alternatives to induced hypertension – AHA/ASA (moderate evidence) 18

Supportive Care

Venous Thromboembolism (VTE) Prophylaxis

Initiate pharmacologic VTE prophylaxis once the aneurysm has been secured – AHA/ASA (Class I, Level B) 16

Imaging Follow‑Up

Obtain immediate post‑treatment vascular imaging to detect residual aneurysm or recurrence – AHA/ASA (Class I, Level B) 16
Perform scheduled follow‑up vascular imaging at 6 months and 18 months; retreat (re‑coiling or repeat clipping) should be strongly considered for clinically significant growing remnants – AHA/ASA (Class I, Level B) 16

Airway Management When Intubation Is Required

Use rapid‑sequence intubation with adequate pre‑oxygenation, pharmacologic attenuation of reflexes, and meticulous avoidance of blood‑pressure swings – AHA/ASA (Class I, Level C) 19

Management of Ruptured Cerebral Aneurysm – Evidence‑Based Recommendations

1. Timing of Aneurysm Securing

Secure the aneurysm as early as possible, ideally within the first 24 hours of symptom onset, because early re‑bleeding carries a mortality of 70‑80 % and early treatment is the only proven intervention to reduce this catastrophic risk 20, 21.

2. Immediate Diagnostic Evaluation

Non‑contrast head CT performed within 12 hours of onset has a sensitivity of 98‑100 %; sensitivity declines to 93 % at 24 hours and to 57‑85 % by day 6 22.
After confirmation of subarachnoid hemorrhage, obtain digital subtraction angiography with three‑dimensional rotational imaging to identify the aneurysm and plan definitive therapy 22.
Assess clinical severity promptly using the Hunt‑Hess or World Federation of Neurological Surgeons (WFNS) scales, as the initial grade is the strongest predictor of outcome 22.

3. Blood‑Pressure Management Prior to Securing

Maintain systolic blood pressure < 160 mm Hg using titratable short‑acting intravenous agents (nicardipine or labetalol) while keeping mean arterial pressure ≥ 65 mm Hg to avoid cerebral hypoperfusion 20.

4. Pharmacologic Neuroprotection

Administer oral nimodipine 60 mg every 4 hours for 21 days, initiating as soon as possible (within 96 hours of SAH onset); nimodipine improves neurological outcomes but does not prevent angiographic vasospasm 22.

5. Selection of Definitive Aneurysm Treatment

5.1 Anterior Circulation Aneurysms

When both endovascular coiling and surgical clipping are technically feasible, endovascular coiling is preferred because it yields superior functional outcomes at one year 20, 21.
In patients younger than 40 years, clipping may be considered to enhance long‑term durability 20.

5.2 Posterior Circulation Aneurysms

For posterior circulation aneurysms amenable to coiling, endovascular treatment is preferred; the relative risk of death or dependence is 0.41 compared with clipping 20, 21.

5.3 Large Intraparenchymal Hematoma with Depressed Consciousness

Emergent surgical evacuation of a large intraparenchymal hematoma in salvageable SAH patients reduces mortality (≈ 27 % vs 80 % with conservative care) 20.

5.4 Wide‑Neck Aneurysms

When clipping or primary coiling is unsuitable, stent‑assisted coiling or flow‑diverter devices are reasonable options to lower re‑bleeding risk 20, 21.

5.5 Fusiform/Blister Aneurysms

Flow‑diverter devices are reasonable for ruptured fusiform or blister aneurysms to reduce mortality 20, 21.

5.6 Contraindicated Use of Stents/Flow‑Dividers

For ruptured saccular aneurysms that are suitable for primary coiling or clipping, stents or flow‑diverters should NOT be used because they increase complication rates, including hemorrhage related to required dual antiplatelet therapy 20, 21.

6. Treatment Goals

Aim for complete aneurysm obliteration whenever technically feasible; incomplete obliteration markedly raises the risk of re‑bleeding and the need for retreatment 20, 21.
If complete obliteration cannot be achieved, a partial treatment that secures the rupture site is acceptable, with planned retreatment within 1‑3 months 20, 21.

7. Management of Hydrocephalus

Acute symptomatic hydrocephalus warrants urgent cerebrospinal‑fluid diversion via external ventricular drainage or lumbar drainage 22, 23.
Chronic symptomatic hydrocephalus should be treated with permanent CSF shunting 23.

8. Transfer to Specialized Centers

Patients should be transferred immediately from low‑volume hospitals (< 10 SAH cases/year) to high‑volume centers (> 35 cases/year) that have experienced cerebrovascular neurosurgeons, endovascular specialists, and multidisciplinary neuro‑intensive care services 23.

9. Management of Delayed Cerebral Ischemia (DCI)

Maintain euvolemia; prophylactic hypervolemia (“triple‑H” therapy) does not improve outcomes and may be harmful 23.
If symptomatic DCI develops, induce hypertension while preserving euvolemia, unless baseline blood pressure is already high or cardiac status precludes it 23.
Consider cerebral angioplasty and/or selective intra‑arterial vasodilator therapy for symptomatic vasospasm that fails to respond promptly to hypertensive therapy 23.

10. Antifibrinolytic Therapy (Limited Use)

Short‑course antifibrinolytics (< 72 hours) such as tranexamic acid or aminocaproic acid may be reasonable only when aneurysm securing is unavoidably delayed, the re‑bleeding risk is high, and no contraindications exist 23.
The ULTRA 2023 trial demonstrated that tranexamic acid does NOT significantly reduce re‑bleeding rates or improve functional outcomes when aneurysms are secured early 20.

11. Vascular Imaging Follow‑up

Obtain immediate post‑treatment vascular imaging to detect residual filling or recurrence that may require further intervention 22.
Schedule individualized follow‑up vascular imaging; retreatment should be strongly considered for clinically significant remnants that enlarge 22.

12. Practices to Avoid

Do NOT postpone aneurysm treatment beyond 24 hours when feasible, as early re‑bleeding risk rises progressively 20, 21.
Do NOT employ prophylactic hypervolemia (“triple‑H”) because it lacks supporting evidence and may cause harm 23.
Do NOT use stents or flow‑diverters for ruptured saccular aneurysms amenable to primary coiling or clipping due to higher complication risk 20, 21.

Evidence Supporting Key Interventions in Subarachnoid Hemorrhage

Proven Effective Interventions

Nimodipine therapy and endovascular aneurysm repair are the only two interventions with strong supporting evidence for improving outcomes after subarachnoid hemorrhage. This conclusion is based on high‑quality data reported in the journal Stroke (2020) and reflects the highest level of evidence currently available for SAH management. 24

Research Gaps

Intensive‑care strategies for subarachnoid hemorrhage lack robust randomized trial data, indicating a need for further high‑quality research to define optimal practices. The same Stroke (2020) source highlights the paucity of strong evidence for many ICU‑based interventions. 24

Evidence‑Based Initial Stabilization and Diagnosis of Subarachnoid Hemorrhage

Airway Management and Early Resuscitation

Immediate assessment and support of airway, breathing, and circulation are essential for all patients presenting with suspected subarachnoid hemorrhage, because rapid neurological deterioration can occur. 25
When endotracheal intubation is required (e.g., due to decreased level of consciousness or inability to protect the airway), rapid‑sequence intubation with thorough pre‑oxygenation, pharmacologic attenuation of reflex sympathetic responses, and strict avoidance of abrupt blood‑pressure changes should be employed. 25
A nasogastric or orogastric tube should be placed right after intubation to lower the risk of aspiration. 25
Oxygenation should be optimized without hyperventilation; continuous pulse‑oximetry and periodic arterial blood‑gas analysis are recommended to guide therapy. 25

Diagnostic Imaging and Laboratory Evaluation

If a non‑contrast head CT performed within the first 6 hours is negative but clinical suspicion for subarachnoid hemorrhage remains high, a lumbar puncture should be obtained to assess for xanthochromia and elevated bilirubin. Spectrophotometric analysis performed more than 6 hours after symptom onset provides ≈ 100 % sensitivity and ≈ 95 % specificity for detecting subarachnoid blood. 25
When conventional digital subtraction angiography cannot be performed promptly, computed‑tomography angiography (CTA) may be used as an alternative; however, selective catheter cerebral angiography remains the gold‑standard technique for definitive aneurysm identification. 25

Clinical Suspicion

Subarachnoid hemorrhage is frequently missed on initial evaluation; clinicians should maintain a high index of suspicion in any patient who presents with an abrupt, severe headache. 25

Acute Management of Subarachnoid Hemorrhage – Evidence‑Based Recommendations

Diagnostic Evaluation

Non‑contrast head CT performed within the first 12 h after symptom onset has a sensitivity of 98–100 %; sensitivity declines to 93 % at 24 h and 57–85 % by day 6. 26
When the initial CT is negative but clinical suspicion remains high (e.g., abrupt severe headache), a lumbar puncture performed > 6 h after onset and analyzed by spectrophotometry detects xanthochromia with 100 % sensitivity and 95 % specificity. 26
Subarachnoid hemorrhage is initially missed in up to 12 % of cases; clinicians should maintain a high index of suspicion for acute severe headache. 26

Airway and Respiratory Management

Rapid‑sequence intubation (with pre‑oxygenation and blunting of sympathetic reflexes) is recommended for patients with decreased consciousness who cannot protect their airway, avoiding blood‑pressure swings. Class I, Level B. 26
Adequate oxygenation should be maintained without hyperventilation, using pulse‑oximetry and periodic arterial blood gases for monitoring. Class I, Level B. 26

Blood‑Pressure Management (Before Aneurysm Securing)

Target a systolic blood pressure < 160 mmHg using short‑acting, titratable IV agents (e.g., nicardipine or labetalol) while keeping mean arterial pressure ≥ 65 mmHg. Class I, Level A. 27

Nimodipine Therapy

Begin oral nimodipine 60 mg every 4 h within 96 h of hemorrhage onset and continue for 21 consecutive days. Class I, Level A. [28][27]

Aneurysm Securing – Timing and Technique

Secure the ruptured aneurysm as early as feasible, ideally within 24 h of presentation; re‑bleeding carries a 70–80 % mortality, with 15 % of re‑bleeds occurring in the first 24 h (70 % within the first 2 h). Class I, Level A. 27
For anterior‑circulation aneurysms amenable to both approaches, endovascular coiling is preferred over surgical clipping because it yields superior 1‑year functional outcomes. Class I, Level A. 27
For posterior‑circulation aneurysms, endovascular coiling markedly reduces the risk of death or dependency (relative risk ≈ 0.41 versus clipping). Class I, Level A. 27
In patients with a large intraparenchymal hematoma (> ≈ 50 cm³) who are comatose but retain spontaneous respiration and pain response, emergent surgical evacuation combined with aneurysm clipping reduces mortality from ~80 % to ~27 %. Class I, Level A. 27

Transfer to Specialized Centers

Patients initially evaluated at low‑volume hospitals (< 10 SAH cases/yr) should be transferred immediately to high‑volume centers (> 35 SAH cases/yr) that have experienced cerebrovascular surgeons, endovascular specialists, and dedicated neurocritical‑care teams. Class I, Level A. 27

Management of Acute Hydrocephalus

When acute symptomatic hydrocephalus develops (occurs in 15–87 % of SAH patients), urgent cerebrospinal‑fluid diversion via external ventricular drainage or lumbar drainage is indicated. Class I, Level B. [28][27]
Do not wean an external ventricular drain over more than 24 h, as prolonged weaning does not lower the need for permanent shunting. Class I, Level B. 28

Prevention and Treatment of Delayed Cerebral Ischemia (DCI)

Maintain euvolemia and normal circulating blood volume to reduce the risk of DCI. Class I, Level B. [28][27]
Avoid prophylactic hypervolemia and “triple‑H” therapy; these strategies lack supporting evidence and may cause harm. Class I, Level B. 27
If symptomatic DCI occurs, induce hypertension while preserving euvolemia, unless baseline blood pressure is already high or cardiac status precludes it. Class I, Level B. [28][27]
For symptomatic vasospasm that does not rapidly improve with hypertensive therapy, consider cerebral angioplasty and/or selective intra‑arterial vasodilator administration. Class IIa, Level B. [28][27]

Antifibrinolytic Therapy (Limited Role)

Short‑term antifibrinolytic therapy (≤ 72 h) with tranexamic acid or aminocaproic acid may be reasonable only when aneurysm securing is unavoidably delayed, the re‑bleeding risk is high, and no contraindications exist. Class IIa, Level B. 27

All recommendations are based on the cited evidence and reflect the strength of recommendation (Class) and quality of evidence (Level) where provided.