392  Crucial  Test  of  Therapeutic  Evidence.       { A™eJt°mbmhil?7 
THE  CRUCIAL  TEST  OF  THERAPEUTIC  EVIDENCE.1 
By  Torald  Sollmann,  M.D.,  Cleveland. 
According  to  the  good  old  truism,  the  last  and  crucial  proof  of 
the  pudding  is  in  the  eating  thereof ;  and  so,  the  last  and  crucial  test 
of  a  therapeutic  agent  is  its  consumption  by  a  patient.  There  is, 
however,  one  essential  difference :  When  the  pudding  is  eaten,  with 
a  sense  of  satisfaction,  we  know  that  it  was  good,  or  at  least  an 
eatable  pudding. 
If  the  patient  improves  after  taking  a  remedy,  we  do  not  yet 
know  that  he  improved  on  account  of  the  remedy.  The  post  hoc 
type  of  reasoning  or  logic  is  not  respectable ;  but  it  is  all  too  apt  to 
creep  in  unawares,  unless  one  takes  great  precautions  indeed. 
Clinical  evidence  needs  especially  to  be  on  its  guard  against  this 
pitfall,  for  the  conditions  of  disease  never  remain  constant ;  nor  is  it 
possible  to  foresee  with  certainty  the  direction  which  they  are  going 
to  take.  It  is  just  this  point  which  makes  the  clinical  evidence  so 
much  more  difficult  to  interpret  than  laboratory  evidence,  in  which 
the  conditions  can  be  more  or  less  exactly  controlled,  and  any 
changes  foreseen.  It  is  on  this  account,  also,  that  clinical  experi- 
ments must  be  surrounded  with  extra  painstaking  precautions. 
In  brief,  while  the  "proof"  of  a  remedy  is  on  the  patient,  that 
is  not  the  whole  story,  but  merely  an  introduction.  The  real  prob- 
lem is  to  establish  the  causative  connection  between  the  remedy  and 
the  events.  The  imperfect  realization  of  this  has  blocked  thera- 
peutic advance,  has  disgusted  critical  men  to  the  point  of  therapeutic 
nihilism,  and  has  fertilized  the  ground  for  the  commercial  exploita- 
tion of  drugs  that  are  of  doubtful  value  or  worse. 
This  has  been  impressed  on  me  particularly  by  my  service  on  the 
Council  on  Pharmacy  and  Chemistry.  In  the  course  of  its  work  of 
passing  on  the  claims  advanced  for  commercial  remedies,  this  coun- 
cil is  forced  to  inquire  critically  into  the  basis  of  the  claims  of  manu- 
facturers. 
It  is  interesting  to  note  the  qualitive  differences  in  the  evidence 
for  the  various  kinds  of  claims :    The  chemical  data  are  usually 
1  Read  before  the  Section  on  Pharmacology  and  Therapeutics  at  the 
Sixty-Eighth  Annual  Session  of  the  American  Medical  Association,  New 
York,  June,  1917,  and  reprinted  from  the  Journ.  A.  M.  A.,  July  21,  1917,  pp. 
198,  199. 
