Clinical Calculators

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Drug Interactions Checker

Common clinically significant interactions — BNF / Stockley's

Enter up to 4 drug names (e.g. warfarin, ibuprofen)

Drug 1

Drug 2

Drug 3 (optional)

Drug 4 (optional)

⚠️ Screening tool only. Always verify with BNF, Stockley's Drug Interactions, or a clinical pharmacist.
References: BNF · Stockley's Drug Interactions · MHRA · SPC

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Renal Dose Adjustment

eGFR & weight-based dose adjustment — BNF / Renal Drug Handbook

Drug

eGFR (mL/min/1.73m²)

Weight (kg)

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CURB-65

Community-acquired pneumonia severity — BTS

New confusion (AMT ≤8 or new disorientation)

Urea >7 mmol/L

Respiratory rate ≥30 breaths/min

BP: systolic <90 or diastolic ≤60 mmHg

Age ≥65 years

BTS CAP Guidelines (2009) · NICE NG138

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CHADS₂ Score

AF stroke risk — original score

Congestive Heart Failure (1 point)

Hypertension (1 point)

Age ≥75 years (1 point)

Diabetes mellitus (1 point)

Prior stroke / TIA (2 points)

Gage BF et al. JAMA 2001 · Superseded by CHA₂DS₂-VASc for clinical use

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PHQ-9

Patient Health Questionnaire — depression severity

Over the last 2 weeks, how often have you been bothered by the following? (0=Not at all, 1=Several days, 2=More than half the days, 3=Nearly every day)

Little interest or pleasure in doing things

Feeling down, depressed, or hopeless

Trouble falling/staying asleep, or sleeping too much

Feeling tired or having little energy

Poor appetite or overeating

Feeling bad about yourself — or that you are a failure

Trouble concentrating on things

Moving or speaking slowly / being fidgety or restless

Thoughts of being better off dead or of hurting yourself

Kroenke K et al. J Gen Intern Med 2001 · NICE NG222

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GAD-7

Generalised Anxiety Disorder — 7 item scale

Over the last 2 weeks, how often have you been bothered by the following? (0=Not at all, 1=Several days, 2=More than half, 3=Nearly every day)

Feeling nervous, anxious, or on edge

Not being able to stop or control worrying

Worrying too much about different things

Trouble relaxing

Being so restless that it is hard to sit still

Becoming easily annoyed or irritable

Feeling afraid as if something awful might happen

Spitzer RL et al. Arch Intern Med 2006 · NICE NG189

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qSOFA

Quick SOFA — sepsis bedside screening

Respiratory rate ≥22 breaths/min

Altered mentation (GCS <15)

Systolic BP ≤100 mmHg

Singer M et al. JAMA 2016 (Sepsis-3) · NICE NG51

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Glasgow Coma Scale

Neurological assessment — Teasdale & Jennett

Eye opening response

Verbal response

Motor response

Teasdale G, Jennett B. Lancet 1974 · NICE NG232

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Child-Pugh Score

Liver disease severity — cirrhosis prognosis

Total Bilirubin

Serum Albumin

INR / Prothrombin time

Ascites

Hepatic Encephalopathy

Child CG, Turcotte JG (1964) · NICE CG165

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APGAR Score

Newborn assessment — 1 and 5 minutes

Appearance (skin colour)

Pulse (heart rate)

Grimace (reflex irritability)

Activity (muscle tone)

Respiration (breathing)

Virginia Apgar 1952 · RCOG / NICE guidance

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Waterlow Score

Pressure ulcer risk — NICE NG179

Build / Weight (BMI)

Skin type / Visual risk areas

Sex / Age

Continence

Mobility

Appetite / Nutritional risk

+4: On steroids / cytotoxics / anti-inflammatory drugs

+4: Smoking / diabetes / peripheral vascular disease

+2: Anaemia (Hb <8)

+5: Major surgery / trauma (orthopaedic / spinal; >2 hours on table)

+4: Neurological deficit (MS, CVA, motor/sensory)

Waterlow J (1985, revised 2005) · NICE NG179

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4AT

Rapid delirium assessment — validated UK tool

1. Alertness (observe)

2. AMT4 — orientation (age, DOB, place, current year)

3. Attention — months of year backwards

4. Acute change or fluctuating course (collateral history)

Bellelli G et al. Age Ageing 2014 · NICE NG119 · validated for UK use

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FRAX Risk Factors

Fracture risk screening — refer to full FRAX calculator

Count major clinical risk factors. Full 10-year probability requires the online FRAX tool (shef.ac.uk/FRAX). This screens for high-risk patients.

Age (years)

BMD T-score (if known)

Previous fragility fracture (doubles risk)

Parent hip fracture

Current smoker

Oral glucocorticoids (>5mg prednisolone/day for >3 months)

Rheumatoid arthritis

Secondary osteoporosis (T1DM, liver disease, COPD)

Alcohol ≥3 units/day

WHO FRAX · NICE NG187 — Osteoporosis · shef.ac.uk/FRAX (full calculator)

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MMSE Interpretation

Mini-Mental State Examination score guidance

Enter the administered MMSE total score (0-30) to get severity classification and guidance per NICE dementia guidelines.

MMSE Total Score (0–30)

Education level (adjusts interpretation)

Folstein MF et al. 1975 · NICE NG97 — Dementia

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QRISK3 (Simplified)

10-year CVD risk — NICE CG181 / QResearch

Approximation based on key QRISK3 variables. For prescribing decisions use the full QRISK3 tool at qrisk.org.

Age

Sex

Systolic BP mmHg

TC:HDL ratio

Smoker status

BMI kg/m²

Systolic BP variability readings

Conditions (tick all that apply)

Atrial fibrillation Type 1 diabetes Type 2 diabetes On antihypertensives Rheumatoid arthritis CKD stage 3–5 Severe mental illness SLE South Asian ethnicity Family Hx CVD <60 Deprivation (Townsend>3) Migraine

QRISK3 — Hippisley-Cox et al. BMJ 2017 · NICE CG181 · Verify at qrisk.org

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HEART Score

Chest pain risk stratification — ACS probability

History

ECG

Age

Risk factors

Troponin (× upper limit of normal)

Six AJ et al. Neth Heart J 2008 · Validated for ED chest pain assessment

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SOFA Score

Sequential Organ Failure Assessment — ICU mortality

PaO₂/FiO₂ ratio mmHg

Platelets ×10³/µL

Bilirubin µmol/L

Cardiovascular

GCS

Creatinine µmol/L

Vincent JL et al. ICM 1996 · Sepsis-3 definition uses SOFA ≥2 change

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HbA1c Converter

IFCC (mmol/mol) ↔ NGSP/DCCT (%) + mean glucose

Enter HbA1c — IFCC mmol/mol

— or —

Enter HbA1c — NGSP %

IFCC conversion · NICE NG28 T2DM targets: 48 mmol/mol (drug-naive), 53 (on drugs/insulin)

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Body Surface Area

Mosteller formula — chemotherapy dosing

Height cm

Weight kg

Mosteller RD. NEJM 1987 · Standard formula for oncology dosing

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MELD Score

Model for End-stage Liver Disease — transplant priority

Creatinine µmol/L

Bilirubin µmol/L

INR

Sodium mmol/L

On dialysis (≥2× weekly)

Kamath PS et al. Hepatology 2001 · MELD-Na (UNOS) used for transplant listing

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IPSS (Prostate)

International Prostate Symptom Score — BPH severity

Score each symptom over the past month: 0=Not at all, 1=<1 in 5, 2=<half the time, 3=About half, 4=>half the time, 5=Almost always

Incomplete emptying

Frequency

Intermittency

Urgency

Weak stream

Straining

Nocturia

Barry MJ et al. J Urol 1992 · NICE NG123 BPH guidelines

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CAGE Questionnaire

Alcohol use disorder screening

Answer Yes / No to each question about the patient's drinking behaviour.

C — Have you ever felt you should Cut down on your drinking?

A — Have people Annoyed you by criticising your drinking?

G — Have you ever felt bad or Guilty about your drinking?

E — Have you ever had a drink first thing in the morning (Eye-opener)?

Ewing JA. JAMA 1984 · Score ≥2 has 93% sensitivity for alcohol use disorder

🧮 Clinical Calculators