Overlevelsesraten

Overlevelsesraten is a statistical measure used in epidemiology and clinical research to describe the proportion of individuals who are alive after a defined period following a diagnosis, treatment, or exposure. It is commonly reported as 1-year, 5-year, or 10-year survival. The most widely used form is the overall survival rate, which counts deaths from any cause, but other forms such as disease-specific or relative (net) survival are also reported.

Survival rates are estimated from patient cohorts using methods such as the Kaplan-Meier estimator or life-table methods. These approaches account for censored data, meaning patients who are lost to follow-up or have not yet reached the end of the observation period. The resulting survival curve shows the probability of surviving beyond each time point. The median survival time is the time by which half the cohort has died. A higher survival rate indicates a better prognosis within the studied context.

Interpretation and limitations: Survival rates depend on factors including disease stage at diagnosis, treatments available, patient age and comorbidity, and changes in medical practice over time. Lead-time bias, length-time bias, and differences between populations can affect comparisons between studies or regions. Survival rates describe outcomes at the population level and do not predict individual risk.

Applications: Survival rates are used for prognosis, patient counseling, treatment evaluation, and health policy planning. They provide a summary measure of outcome but do not convey individual risk, which requires clinical factors and possibly other models.