Name: life table method for survival rates
Uploaded: 2025-01-09T15:14:16.000Z
Duration: 1 min 20 s
Channel: JoVE

ניתוח הישרדות מעריך את הזמן עד להתרחשות אירוע כגון מוות או כישלון טיפולי. הגישה האקטוארית או טבלת החיים, המותאמת למדע האקטואריה, מנתחת נתוני הישרדות.
בתרחיש מחקר קליני, המשתתפים מחולקים לקבוצות עם משכי מעקב שונים כדי להתמקד בתקופות קריטיות, כגון השנה הראשונה לאחר ניתוח בסיכון גבוה.
השיטה האקטוארית מחשבת את שיעורי ההישרדות בפרקי זמן קבועים מראש, תוך ניצול מלא של נתונים מכל המשתתפים, כולל אלה שאבדו במעקב או שמתו מסיבות אחרות.
כדי להבין את ההשפעה על הישרדות בשנה הראשונה, שיעורי הישרדות של שנה אחת נגזרים על ידי הפחתת מספר מקרי המוות מכלל המשתתפים וחלוקה במספר המקורי.
רק תת-קבוצה של חולים שנצפתה במשך השנתיים המלאות נחשבת להערכת הישרדות של שנתיים, תוך התמקדות באלה ששרדו את השנה הראשונה ולאחר מכן המשיכו לשרוד את השנה השנייה.
שיטה זו עקבית, מסייעת לזהות מגמות ארוכות טווח ומעריכה את יעילותם של טיפולים או התערבויות, ומספקת כלי חזק להבנת תוצאות במחקר רפואי.

הגישה האקטוארית

Actuarial Approach

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הגישה האקטוארית, שהיא שיטה סטטיסטית שנועדה במקור להערכת סיכון לביטוח חיים, נמצאת בשימוש נרחב לחישוב שיעורי הישרדות במחקרים קליניים ובחקר אוכלוסיות. שיטה זו מתחשבת במשתתפים שאיבדו אותם לעקוב אחרי המחקר או אלו שמתו ממחלות שלא קשורות למחקר, ומספקת ייצוג מדויק יותר של סבירות ההישרדות.

נשקול את הדוגמה של הליך כירורגי בסיכון גבוה עם שיעורי תמותה משמעותיים בשלב מוקדם. נערך מחקר קליני בן שנתיים, שמתמקד בשנה הקריטית הראשונה. המשתתפים מחולקים לשתי קבוצות: אחת נבדקת במשך שנה והשנייה במשך שנתיים. שיעורי ההישרדות מוערכים באמצעות השיטה האקטוארית (או שיטת לוח החיים), שמחלקת את תקופת המחקר לאינטרוולים—בדרך כלל שנה אחת.

להמחשה, נניח שהקבוצה הראשונה מתחילה עם 1,000 חולים, מהם 240 נפטרים בשנה הראשונה. הקבוצה השנייה גם מתחילה עם 1,000 חולים, עם 200 מיתות בשנה הראשונה ו-16 בשנה השנייה. שיעור ההישרדות בשנה אחת מחושב על ידי חיסור סך המיתות ממספר המשתתפים ההתחלתי וחלוקתו במספר האנשים שנכנסו למחקר:

שיעור הישרדות בשנה אחת = (2000−240−200)/2000 = 0.78 או 78%

גישה זו יכולה גם להיות מיושמת במחקרים על תוצאות ארוכות טווח, כמו הערכת היעילות של טיפול בסרטן במשך שנים. השיטה האקטוארית מתחשבת במטופלים שאיבדו קשר או שמתו ממחלות שאינן קשורות למחקר, ומאפשרת ניתוח חזק של השפעות ארוכות טווח.

ליחסי הישרדות לשנתיים, החישוב נעשה מורכב יותר. הוא משתמש בהסתברות מותנית, תוך התחשבות רק באותם אנשים שנצפו במהלך השנתיים המלאות ושרדו את השנה הראשונה. שיעור ההישרדות לשנתיים לא יכול לעלות על שיעור ההישרדות לשנה אחת, והוא נקבע על ידי הכפלת ההסתברות להישרדות בשנה הראשונה בהסתברות להישרדות בשנה השנייה, בהנחה שהאדם שרד את השנה הראשונה.:

שיעור הישרדות לשנתיים = 0.78 × 0.98 = 0.7644 או 76.44%

שיטה מתקדמת זו, למרות שהיא עוצמתית, נתקלת באתגרים כמו נתונים חסרים על מעקב ודיווח מדויק של מקרי המוות. למרות מגבלות אלו, היא נותרת יעילה במיוחד במחקרים באוכלוסיות רחבות בהן קשה לעקוב אחרי משתתפים בודדים. על ידי התחשבות בהסרת נתונים והסתברויות הישרדות לפי אינטרוולים, הגישה האקטוארית מספקת מסגרת אמינה לניתוח הישרדות בהקשרים מחקריים שונים.

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ניתוח הישרדות מעריך את הזמן עד להתרחשות אירוע כגון מוות או כישלון טיפולי. הגישה האקטוארית או טבלת החיים, המותאמת לגישה אקטוארית ...

Education

JoVE Core

Statistics

סטטיסטיקה

Unit 1

יחידה 1

Survival Analysis

ניתוח הישרדות

KEY TERMS AND CONCEPTS

מונחים ומושגי מפתח

life table method for survival rates

The life table method, also called the actuarial approach, is used to estimate survival rates in clinical and population studies. It began in life insurance, where risk over time must be measured carefully. In health research, it gives a clearer picture of survival when some participants are lost to follow-up or die from causes unrelated to the study.

This method works by dividing the study period into set intervals, usually one year. That makes it useful for tracking outcomes over time, especially in studies with early deaths after a high-risk surgical procedure. In one example, a two-year study follows two groups. One group is observed for one year, and the other is observed for two years.

The one-year survival rate is found from the starting group size and the number of deaths during that year. In the example, 1,000 patients begin in each group. The first group has 240 deaths in the first year, and the second group has 200 deaths in the first year. Using the actuarial calculation, the one-year survival rate is 78%.

The same method can also be used for long-term studies, such as testing how well a cancer treatment works over several years. It accounts for patients who are not followed for the full study or who die from unrelated causes. That makes the survival estimate more realistic when individual tracking is difficult.

Two-year survival uses conditional probability, which means the second year is calculated only for people who survived the first year and were observed for the full two years. In the example, the second-year survival probability is multiplied by the first-year survival probability. The result is 0.78 times 0.98, or 76.44%.

A two-year survival rate should not be higher than the one-year rate. The method is powerful, but it depends on complete follow-up and accurate death records. Even with those limits, it is especially useful in large population studies where following each person closely is not practical.

Life Table Method for Survival Rates

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actuarial approach

The life table method, also called the actuarial approach, is used to estimate survival rates in clinical and population studies. It began in life insurance, where risk over time must be measured carefully. In health research, it gives a clearer picture of survival when some participants are lost to follow-up or die from causes unrelated to the study. This method works by dividing the study period into set intervals, usually one year. That makes it useful for tracking outcomes over time,...

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Learn how the life table method, or actuarial approach, estimates one-year and two-year survival rates while accounting for follow-up losses and unrelated deaths.

Life Table Method for Survival Rates | JoVE K12

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Life Table Method for Survival Rates

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