First trimester miscarriages in Denmark 1998-2007 (updated April 5, 2008)

Responsible: Christina H. Vestergaard and Øjvind Lidegaard

1.0  Miscarriages in Denmark, 1998-2007. N=90,016

Same in per cent

Comments: The total number of first trimester miscarriages have been fairly constant through the last
ten years. The proportion of missed abortion has increased from 41% in 1998 to 47% in 2007.

1.1  First trimester miscarriages at different departments in 2007 (N=8,937)

Same in per cent

Comments: The proportion of missed abortion among women with miscarriages ranged in 2007
from 35% to 60% at different departments.

1.3  Spontaneous abortions at different departments in 2007
        Incomplete: 1,507 (32%). Complete: n= 3,214 (68%)

Comments: Some departments have a high majority of incomplete spontaneous abortions while others have a
clear majority of complets spontaneous abortions. These proportions are relatively stable from year to year at a
certain department. These differences suggest a different coding practice at different departments.

1.4     Proportion (%) of women with spontaneous abortion surgically evacuated
           at different departments in 2007.  
           Incomplete: 1,507. Complete: n= 3,214. Evacuated: 598 (13%)
           Per cent indicated above each column, absolute number of evacuations in italic inside each column

 
Comments: As compared with the overall average of 13%, some departments have three times the
frequency of evacuations, while other departments have an evacuation rate of less than one half of the average.
Of the 598 evacuated women, 530 (89%) had an incomplete abortion coded, 11% a compete abortion code.
10 (1.7%) were mis-coded with a KLCA code instead of the correct KMBA code.
With a standard of less than 20% evacuated women, 18 (77%) out of 20 departments fulfill this standard.
The rate ratio between highest (36.5% in Esbjerg) and lowest (4.9% in Hvidovre) evacuation
rate has decreased from 8.3 in 2006 to 7.5 in 2007. It is the same departments, which have a high
percentage of incomplete abortions as have a high rate of evacuations. 

1.5   Association between the percentage of incomplete abortions (x-axis) and
          and the evacuation rate (y-axis). Figures from 2007

Comments: For each 10% the proportion of incomplete abortions increase, the evacuation rate
increases with 5%, according to the linear regression line.

1.6   Evacuation in 1st trimester spontaneous abortion 1998-2007. N=50,010, n=9,763
Comments: The proportion of women undergoing evacuation fell from one third in 1998 to 13% in 2004,
and has been stable since then.

1.7  Evacuation rate in women with missed abortion in Denmark 1998-2007.

Comments: The proportion of women with missed abortion undergoing surgical evacuation has been
fairly stable on 64% since 2004.

1.8   Surgical treatment of missed abortion at different departments in 2007
        Per cent evacuated indicated in top of each column, absolute number of evacuated
        indicated in italics in bottom of each column.

Comments: The proportion evacuated ranged from 47% (Frederiksborg) to 81% (Silkeborg).

1.9  Medical treatment (%) of women with missed 1. trimester abortion in
       Denmark 2000-2007. N = 32,511. n = 2,014.

Comments: We have seen a steady increase in medical treatment codes (BKHD50/52). However,
¨more than 13% of the 35% women with missed aborition without a surgical code recorded have
received medical treatment. So we expect a further increase in the medical treatment group the
next years.

1.10  Medical treatment of women with missed abortion at different departments
          in 2007.  Per cent medically treated in top of each column, absolute number of treated
          indicated in italics in bottom of each column. N = 4,216, n = 525

Comments: On average 12.5% of women with missed abortion are coded with a medical treatment
code (BKHD50/52). 64.4% are coded with an evacuation code, leaving 23% without a treatment
code. The majority of these women probably have been treated medically.

1.11  The proportion of women with missed abortion being coded with either
         a surgical code or a medical treatment code at different departments 2007

Comments: The proportion without a surgical or medical treatment code ranged from 10% to 41%
at different departments. There is thus room for an improvement of the coding quality at the majority
of departments.

1.12   Proportion of evacuated women with missed abortion after medical treatment
          at different departments in 2007. N = 525, n = 133.

Comments:  Due to small numbers at each department, much of the variation is due to statistical
chance. Note, that in total 25% of women treated medically for missed abortion ultimately end up
with an evacuation. Therefore a high primary evacuation rate is acceptable for missed abortion.