http://en.wikipedia.org/wiki/Number_needed_to_treat

http://cmp-manual.wbs.cz/-_grafika_webu_-/top_line.jpgDOPLŇKY / STATISTIKA
Hodnocení výsledků studií

  Experimental group (E) Control group (C) Celkem
Events (E) EE = 15 CE = 100 115
Non-events (N) EN = 135 CN = 150 285
Total subjects (S) ES = EE + EN = 150 CS = CE + CN = 250 400
Event rate (ER) EER = EE / ES = 0.1, or 10% CER = CE / CS = 0.4, or 40%  
       
CER − EER < 0: absolute risk reduction ARR (−)0.3, or (−)30%
> 0: absolute risk increase ARI  
(CER − EER) / CER < 0: relative risk reduction RRR (−)0.75, or (−)75%
> 0: relative risk increase RRI  
1 / (CER − EER)
< 0: number needed to treat
NNT (−)3.33
> 0: number needed to harm NNH  
EER / CER relative risk RR 0.25
(EE / EN) / (CE / CN) odds ratio OR 0.167
EER − CER attributable risk AR (−)0.30, or (−)30%
(RR − 1) / RR attributable risk percent ARP  
 
Příklad  - studie ECASS 3
  Experimental group (E) Control group (C) Celkem
Events (E) (mRS 0-1) EE = 219 CE = 182 401
Non-events (N) (mRS>2) EN = 199 CN = 221 420
Total subjects (S) ES = EE + EN = 418 CS = CE + CN = 403 821
Event rate (ER) EER = EE / ES = 0.52, 52% CER = CE / CS = 0.45, or 45%  
       
CER − EER  < 0: absolute risk reduction ARR −0.07, −7%
 > 0: absolute risk increase ARI  
(CER − EER) / CER  < 0: relative risk reduction RRR −0.16, −16%
 > 0: relative risk increase RRI  
1 / (CER − EER)
 < 0: number needed to treat
NNT 14.3
 > 0: number needed to harm NNH  
EER / CER  relative risk RR 1.2
(EE / EN) / (CE / CN)  odds ratio OR 1.34

  Vstupní  hodnoty 
Počet non-eventů (EN)
Počet non-eventů (CN)
 Výsledky 
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