出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/10/24 14:42:53」(JST)
Patients with a certain disease (for example, colorectal cancer) can die directly from that disease or from an unrelated cause (for example, a car accident). When the precise cause of death is not specified, this is called the overall survival rate or observed survival rate. Doctors often use mean overall survival rates to estimate the patient's prognosis. This is often expressed over standard time periods, like one, five, and ten years. For example, prostate cancer has a much higher one year overall survival rate than pancreatic cancer, and thus has a better prognosis.
When someone is interested in how survival is affected by the disease, there is also the net survival rate, which filters out the effect of mortality from other causes than the disease. The two main ways to calculate net survival are relative survival and cause-specific survival or disease-specific survival.
Relative survival has the advantage that it does not depend on accuracy of the reported cause of death; cause specific survival has the advantage that it does not depend on the ability to find a similar population of people without the disease.
Relative survival is calculated by dividing the overall survival after diagnosis of a disease by the survival as observed in a similar population that was not diagnosed with that disease. A similar population is composed of individuals with at least age and gender similar to those diagnosed with the disease.
Cause-specific survival is calculated by treating deaths from other causes than the disease as withdrawals from the population that don't lower survival, comparable to patients who are not observed any longer, e.g. due to reaching the end of the study period.
Median survival is also commonly used in regards to survival rates, meaning the amount of time at which 50% of the patients have died and 50% have survived.[citation needed]
Five-year survival rate measures survival at 5 years after diagnosis.
In cancer research, various types of survival rate can be relevant, depending on the cancer type and stage. These include the disease-free survival (DFS) (the period after curative treatment [disease eliminated] when no disease can be detected), the progression-free survival (PFS) (the period after treatment when disease [which could not be eliminated] remains stable, that is, does not progress), and the metastasis-free survival (MFS) or distant metastasis–free survival (DMFS) (the period until metastasis is detected). Progression can be categorized as local progression, regional progression, locoregional progression, and metastatic progression.
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| リンク元 | 「疾患と死亡に関わる疫学指標」「生存率」「survivorship」「mean survival time」 |
| 拡張検索 | 「five-year survival rate」 |
| 関連記事 | 「rate」「rat」「survival」 |
| 定義 | 特徴 | 式 | ||
| 罹患率 | incidence rate | 単位人口(暴露人口、危険人口)に対する一定期間内に新たに疾病異常者となった者の割合 | 動的 | 一定の観察期間内に新規発生した患者数 [人] / 危険暴露人口一人一人の観察期間の総和 [人年] |
| 有病率 | prevalence rate | 単位人口に対する一時点における疾病異常者の割合 | 静的 | 集団のある一時点における疾病を有する者の数[人] / 集団の調査対象全員の数[人] |
| 死亡率 | mortality rate | 単位人口に対する一定期間内における死亡数の割合 | 集団のある一定期間内における死亡者数[人] / 集団の調査対象全員の数[人] | |
| 致命率 | case fatality rate | 一定期間内において、対象とする疾患にかかった者がその疾患で死亡する者の割合 | 急性疾患の重篤度を表す。 | 死亡率 / 罹患率 |
| 生存率 | survival rate | 対象とする疾患に罹患しているのものが、一定期間中に死亡から免れる確率 | 慢性疾患の予後判定に用いられる。 | (1-死亡率)の積和 |