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# st: RE: Analysing patient's admission over time

 From Nick Cox To "'statalist@hsphsun2.harvard.edu'" Subject st: RE: Analysing patient's admission over time Date Thu, 10 Nov 2011 08:48:45 +0000

```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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```