1,329 calculators and references across 60 specialties, with formula confidence shown up front.
QDiabetes Risk Algorithm: Explanation and Clinical Context QDiabetes is a validated risk prediction tool designed to estimate the 10-year risk of developing type 2 diabetes in adults. It uses demographic and clinical variables readily available in primary care, including age, sex, BMI, family history of diabetes, smoking status, ethnicity, and deprivation score. The algorithm applies a logistic regression model to co
Qp Qs Ratio Calculator Summary and Clinical Context The Qp Qs ratio is a Doppler based calculation used to quantify the relationship between pulmonary blood flow and systemic blood flow. It is an essential parameter when evaluating patients with suspected intracardiac shunts such as atrial septal defect, ventricular septal defect, or patent ductus arteriosus. Doppler echocardiography provides a noninvasive method to
QRISK3: Comprehensive Explanation and Clinical Context The QRISK3 score is a predictive algorithm designed to estimate the 10-year risk of developing a cardiovascular event (such as myocardial infarction or stroke). It represents the third-generation update of the QRISK series developed in the United Kingdom by Hippisley-Cox and Coupland. QRISK3 integrates both classical and novel risk factors including age, sex, sys
QRS Duration Index: Explanation and Clinical Context The QRS Duration Index (QRSd Index) is a heart rate–corrected measure of ventricular depolarization duration, initially described by Brodie et al. in 1982. It is calculated by dividing the QRS duration (in milliseconds) by the square root of the RR interval (in seconds). This index accounts for heart rate variability when assessing intraventricular conduction and c
QRS Width >150 ms Response Ratio: Explanation and Clinical Context The QRS Width >150 ms Response Ratio is derived from the MADIT-CRT trial, which studied the effect of cardiac resynchronization therapy (CRT) in patients with mild heart failure and wide QRS complexes. Patients with a QRS duration greater than 150 ms had a significantly higher likelihood of favorable response to CRT compared to those with narrower QRS
QRS-T Angle Index: Explanation and Clinical Context The QRS-T angle represents the spatial difference between the depolarization (QRS) and repolarization (T wave) vectors of the heart on a 12-lead ECG. A wider QRS-T angle is associated with abnormal ventricular repolarization and is a strong predictor of adverse cardiovascular events, including sudden cardiac death and all-cause mortality. Normal values are usually <
QRSD Ratio (Bundle Branch Differentiation): Explanation and Clinical Context The QRSD Ratio is a metric used to differentiate types of bundle branch conduction delays on ECG, especially in borderline QRS prolongation cases. It is calculated by dividing the QRS duration (ms) by the square root of the RR interval (ms), providing heart rate–corrected QRS assessment. A QRSD ratio <1.15 is typically considered normal, ind
Respiratory RateEnter 1 if respiratory rate is 22 breaths per minute or higher otherwise enter 0 qSOFA Quick Sepsis Assessment Explanation and Clinical Context qSOFA is a rapid bedside tool designed to identify patients with suspected infection who are at increased risk for adverse outcomes such as prolonged intensive care stay and mortality. The score uses three simple clinical variables which are respiratory rate o
QTc Bazett Formula: Explanation and Clinical Context The QT interval represents the time from the start of ventricular depolarization to the end of ventricular repolarization on an electrocardiogram (ECG). QT interval duration varies with heart rate, and QTc (corrected QT) is calculated to standardize QT for heart rate. Bazett's formula is the most widely used correction: QTc = QT / √RR, where QT is in milliseconds a
Comprehensive explanation and clinical context The QT interval measures ventricular depolarisation and repolarisation on the electrocardiogram. Correcting the QT interval for heart rate yields QTc. Several correction formulae exist. Bazett's formula divides QT by the square root of the RR interval in seconds. Fridericia's formula divides QT by the cube root of the RR interval. Framingham's formula adjusts QT by addin
QTc Fridericia Correction: Explanation and Clinical Context The Fridericia formula is used to correct the QT interval for heart rate: QTcF = QT / (RR^1/3), where RR is the interval between heartbeats in seconds. It provides a more accurate correction than Bazett's formula, especially at extreme heart rates. QTc prolongation is associated with increased risk of ventricular arrhythmias, including Torsades de Pointes, a
Quick SOFA (qSOFA) Score: Explanation and Clinical Context The Quick Sequential Organ Failure Assessment (qSOFA) score was proposed by the Sepsis-3 task force (Singer et al., 2016) as a simplified bedside tool to identify patients with suspected infection at greater risk for poor outcomes outside the intensive care unit. It uses three simple clinical criteria: respiratory rate > 22 breaths per minute, systolic blood
QUICKI Insulin Sensitivity Index Explanation and Clinical Context QUICKI is a validated surrogate marker to estimate insulin sensitivity that uses fasting glucose and fasting insulin values. It provides a simple and reproducible method to screen metabolic health in clinical and research settings. The mathematical structure of QUICKI gives a continuous scale where lower values reflect diminished insulin sensitivity su