Kappa statistic (κ)
A measure of the extent to which observers achieve agreement beyond the level expected to occur by chance alone. Kappa can take values from 0 (poor agreement) to 1.0 (perfect agreement).

Karnofsky performance score
A measure of a patient’s functional capacity used to determine performance status. It ranges from 100%, signifying normal functional status with no evidence of disease, to 0%, signifying death.

Kernig signs
Meningeal inflammation and irritation that elicits a protective reflex to prevent stretching of the inflamed and hypersensitive nerve roots, which is detectable clinically as neck stiffness or Kernig or Brudzinski signs. Originally, the Kernig signs were present when patients sat on the edge of a bed with their legs dangling and an attempt to extend the knee joint more than 135 degrees, or in severe cases more than 90 degrees, elicited spasm of the extremity that disappeared when the patients lay supine or stood up. Today, the maneuver is most commonly performed with the patient lying supine and the hip flexed at 90 degrees. A positive sign is present when extension of the knee from this position elicits resistance or pain in the lower back or posterior thigh.

Konno score
A clinical diagnostic support tool using combinations of history and physical examination used for diagnosising lumbar spinal stenosis. Konno S, Hayashino Y, Fukuhara S, et al. Development of a clinical diagnosis support tool to identify patients with lumbar spinal stenosis. Eur Spine J. 2007; 16(11):1951 1957. [PMID: 17549525]

Korotkoff sounds
Noise heard over an artery when pressure over it is reduced below systolic arterial pressure, as when blood pressure is determined by the auscultatory method.

Kruis model
A logistic model that contains signs and symptoms useful for diagnosing irritable bowel syndrome. See Table 55-6 in The Rational Clinical Examination.

Kussmaul sign
The paradoxic increase in the height of jugular venous pressure that occurs during inspiration. This sign is most commonly caused by severe right-sided heart failure, regardless of etiology.