On 07-Mar-05 Ted Harding wrote:
> On 07-Mar-05 Ted Harding wrote:
>>[...]
>> which it seems was released this morning, and this in turn
>> led to a PDF file of numbers and rates for the different
>> Trusts for 2001-4 by 6-monthly intervals:
>>
>> http://www.dh.gov.uk/assetRoot/04/10/55/18/04105518.pdf
>>
> [...]
> Well, I've now done this file manipulation (I hope correctly)
> for the General Acute Trusts at the beginning of this dataset.
>
> Using a crude (Sum(cases))/(Sum(cases/rate)) I get (as returned
> from the software):
>
> Apr2001-Sep2001: 0.1368885
> Apr2002-Sep2002: 0.1430201
> Apr2003-Sep2003: 0.1494563
> Apr2004-Sep2004: 0.1490701
>
> Oct2001-Mar2002: 0.1417535
> Oct2002-Mar2003: 0.1611403
> Oct2003-Mar2004: 0.1641550
> [...]

There are now results at

http://www.hpa.org.uk/infections/topics_az/staphylo/
staphyl_six_monthly.htm

where you can find 5 graphs.

For England, total of all Trust types (Fig.3) the graphs
are also annotated with the numbers, giving (for numbers,
and rates per 100 bed days):

Apr2001-Sep2001:  3598  0.17
Apr2002-Sep2002:  3574  0.171
Apr2003-Sep2003:  3744  0.178
Apr2004-Sep2004:  3519  0.168

Oct2001-Mar2002:  3651  0.172
Oct2002-Mar2003:  3799  0.182
Oct2003-Mar2004:  3940  0.188

The graphs also show "error bars" for rates which, by eye,
seem to be about +/- 0.005 in each case.

Thus it would indeed seem that for the Summer periods the
rate dropped in Apr2004-Sep2004. However, it is pointed
out that the bed occupancy data used to calculate this
rate refer to the previous period, since they have not
yet been made available (the bed occupancy data for the
other periods are concurrent, however). Therefore the
rate for Apr2004-Sep2004 is not on the same footing as
the others, so still cannot be completely trusted.

The Winter data, however, have showed a steady increase
from year to year.

In Fig.1 (rates by type of Trust: General Acute, Specialist
and Single Specialty) it can be seen (though numbers are
not given) that

a) Specialist Trusts have the highest rates (ca. 0.23),
   and (except for Apr2004-Sep2004), taking error bars
   into account, the rates are consistent with a steady
   slight rise, or steady slight fall, either over all
   consecutive periods or over successive Winter periods
   and succesive Summary periods. Apr2004-Sep2004 is,
   however, distinctly lower than the others (ca. 0.20),
   but is of course subject to the same caveat as above.

b) General Acute Trusts have the next highest (ca. 0.15)
   fluctuating up and down between Summer (low) and Winter
   (high) but with a clear increase over Summar periods and
   a clear increase over Winter periods.

c) Single Specialty Trusts have the lowest (0.07-0.10)
   with perhaps on overall downward trend since Apr2002,
   though the error bars are so wide that no clear inference
   is possible.

From the above, I'm inclined to surmise that the reduction
in MRSA which people have been crowing about probably comes
from the marked reduction in Specialist Trusts, there being
nothing to crow about in the others.

Best wishes to all,
Ted.


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Date: 08-Mar-05                                       Time: 10:00:53
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