st: RE: Analysing patient's admission over time

[Nick Cox <n.j.cox@durham.ac.uk>]

Use technique such as 

bysort pseudoid quarter primary : gen admissions_primary = _N
by pseudoid quarter : gen admissions_any_reason = _N 

l if primary == "560.9" & admissions_primary > 1  

For a tutorial, see 

SJ-2-1  pr0004  . . . . . . . . . . Speaking Stata:  How to move step by: step
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q1/02   SJ 2(1):86--102                                  (no commands)
        explains the use of the by varlist : construct to tackle
        a variety of problems with group structure, ranging from
        simple calculations for each of several groups to more
        advanced manipulations that use the built-in _n and _N

Nick 
n.j.cox@durham.ac.uk 

Dudekula, Anwar

I am analyzing a data set containing de-identified patients with crohns disease or ulcerative colitis-UC admitted to the hospital over time .
A part of the dataset admitted for  is pasted below.( after removing the identifiers) 

It contains  

1)patients pseudoid( distinct for each person)-String variable 
2)Primary diagnosis crohns disease or ulcerative colitis)-numeric value(0/1)
3)age -Numeric value
4)Primary diagnosis (ICD9 code , string value) 
5)Secondary diagnosis (ICD9code, string value) 
6)admission over quarter of year( first-Q1;Second-Q2;third-Q3 and forth -Q4)-Numeric value(1,2,3,4) 
 
     +------------------------------------------------------------------+
     |   pseudoid      crohns      UC  age  Primary  Secondary     quarter |
					                       diagnosis diagnosis
     |------------------------------------------------------------------|
  1. | pseudoid1     Crohns   No UC    57   560.9   555.9          Q4 |
  2. |  pseudoid2     Crohns   No UC    32   555.0   560.9          Q4 |
  3. | pseudoid3   No Crohns      UC    83   584.9   276.2          Q1 |
  4. | pseudoid1   No Crohns      UC    78   578.9   285.1          Q4 |
  5. | pseudoid2   No Crohns      UC    63   038.9   584.9          Q2 |
  6. | pseudoid3      Crohns   No UC    60   555.1   285.1          Q2 |
  7. | pseudoid4   No Crohns      UC    60   V55.2   556.8          Q3 |
  8. | pseudoid5      Crohns   No UC    42   579.3   555.9          Q4 |
  9. | pseudoid6      Crohns   No UC    23   566     682.5          Q4 |
 10. | pseudoid1   No Crohns      UC    22   556.9   276.51         Q1 |
     +------------------------------------------------------------------+

Questions: 

1)How do I identify patients( and their age, diagnosis , associated secondary diagnosis) who had repeated admissions( Eg more than one admission) over each quarter of the year
2)How can I subset those patients 
3)Most common secondary diagnosis in patients with primary diagnosis of Crohns or ulcerative colitis 


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