The random thoughts of a sceptical activist

Monthly Archives: October 2014

An idiot’s guide to understanding NHS homeopathy prescription data

A guide for the clueless

When writing Nightingale Collaboration newsletters, I presume readers have some basic science, search, maths and critical thinking skills. I’m sure this covers a good proportion of readers, but there seem to be some who are somewhat more challenged in these areas.

Some homeopathy supporters seem particularly inept when it comes to verifying evidence, data, facts and generally looking stuff up. Proper research seems well beyond their abilities.

In the newsletter The decline of homeopathy on the NHS, I gave links to the original Government sources for the data I used. This is certainly more than sufficient for any reasonably capable reader to use to verify the figures and charts I had created, but not, it seems for some.

So, to show how I arrived at the charts that shows the decline of homeopathy on the NHS, this is an appropriately named idiot’s guide to accessing and extracting the data from the original Government source and checking the charts.

Here’s one of the charts that some homeopathy supporters didn’t seem to like.

The decline of homeopathy in the NHS (number of prescription items)

Figure 1: The decline of homeopathy in the NHS (number of prescription items)

I can understand why homeopaths might not like it, but letting their beliefs get in the way of reality is their problem.

One particular homeopathy supporter apparently believed that searching the HSCIC website using the words I used in the title of the chart and getting no results was sufficient ‘research’ to proclaim triumphantly:

Tweet - redacted to protect the guilty

Tweet – redacted to protect the guilty

(Click on the image to see a larger HSCIC search page screenshot.)

That would appear to be the limit of her ‘research’ abilities.

Curiosity is what makes a scientist: not being satisfied with not knowing, not understanding; being inquisitive; not giving up at the first hurdle; pushing on and on…

Homeopaths on the other hand seem content with anything that confirms their  beliefs — particularly if it saves them having to think for themselves.

Data extraction and analysis

So, for those unable to do see how to do it for themselves, here’s where the data come from and how they were extracted to form the charts.

As I said in the newsletter, there are two websites for the data: the HSCIC website for data since 2004 and the National Archives for older data. The HSCIC is the Health and Social Care Information Centre, the Government body that collects these data — and much more besides — and is the official source for all NHS data.

The data I used are the Prescription Cost Analysis (PCA) data. This gives data on all English NHS prescriptions fulfilled in community pharmacies. The HSCIC website search for these data returns links to pages for each year. This is published in April of each year, so the latest is the data for 2013.

Let’s take the data for 2013 as an example, but this applies to all years.

Clicking on the page for that year gives Prescription Cost Analysis, England – 2013.

The source data are listed at the bottom under the heading Resources. The one of interest here is the zip file that contains all the original data rather than the other files, which are just summaries, etc. So, in this case, the file required is Prescription Cost Analysis, England – 2013: Tables [.zip]. This file is 2.3 MB.

This is a zip file, but most computers should be able to open it. In the zip file is an Excel spreadsheet, pres-cost-anal-eng-2013-tab.xls. This file is over 7 MB. Opening this in Excel gives a work book with seven tabs. The lowest level source data is the tab called ‘Individual Preparations’. This spreadsheet has over 23,000 rows and 17 columns of data, giving nearly 400,000 cells of data.

Some familiarity with Excel has to be assumed here. If anyone doesn’t know what Excel is, doesn’t have it or can’t competently use it, then that’s not my problem. If your computer can’t handle large spreadsheets, that’s your problem too.

These data are identified by the type of prescription according to the classes in the British National Formulary (BNF). Prescriptions for homeopathy products are categorised under the single class of Chapter 2, Section 3, Paragraph 3, Sub Paragraph 0, ie BNF 19.2.3.0.

We only need one row: the one for homeopathic prescriptions. In this file, it is row 12,331. It can also be found by searching for ‘homeopathy’: this is worth doing anyway to check there are no other rows for homeopathy. This row has the correct BNF class as given above. The BNF SUB PARAGRAPH NAME is ‘Homeopathic Preparations’.

The columns of interest are the ones headed ‘Items (thousands)’ and ‘NIC £ (thousands)’. ‘Items’ is the number of prescription items and NIC is the Net Ingredient Cost, the basic cost per item, before discounts and does not include any dispensing costs or fees. These terms are defined in the Glossary.

From the 2013 data for Homeopathic Preparations, the figures are:

  • Items (thousands): 13.001
  • NIC £ (thousands): 137.298

This is 13,001 prescription items at a total cost of £137,298.

These figures can be checked by looking at the tab called ‘Totals for BNF Sub Paragraphs’. This totals all the data by BNF sub paragraphs and row 336 confirms the above figures and that we have not missed any data in the ‘Individual Preparations’ tab.

The charts I created use these data and the data obtained in exactly the same manner for the other years. Collating the data for each year from 1995 to 2013 from the respective spreadsheets and putting them into a table gives:

Year

Prescription Items

Net Ingredient Cost

Cost/item

1995

164,207

£816,798

£4.97

1996

172,013

£914,983

£5.32

1997

162,421

£937,311

£5.77

1998

157,063

£927,633

£5.91

1999

147,769

£888,274

£6.01

2000

134,164

£831,130

£6.19

2001

127,333

£807,125

£6.34

2002

117,989

£778,749

£6.60

2003

103,940

£714,938

£6.88

2004

94,501

£661,469

£7.00

2005

82,960

£593,316

£7.15

2006

62,679

£442,769

£7.06

2007

49,316

£321,418

£6.52

2008

26,337

£152,300

£5.78

2009

19,005

£100,486

£5.29

2010

16,359

£121,449

£7.42

2011

15,501

£130,601

£8.43

2012

15,262

£143,068

£9.37

2013

13,001

£137,298

£10.56

 

Charting these data gives the charts here and in the newsletter.

The decline of homeopathy on the NHS (prescription costs)

Figure 2: The decline of homeopathy on the NHS (prescription costs)

The third chart, the average cost per prescription item, is simply the total cost per annum divided by the number of prescription items and can be checked with a calculator.

The rising cost of homeopathy in the NHS (average cost per prescription item)

Figure 3: The rising cost of homeopathy in the NHS (average cost per prescription item)

For anyone who’s interested, the above is more than sufficient to check each chart back to the original, authoritative source data to ensure the charts are accurate.

These data clearly demonstrate to all but the most clueless that homeopathy on the NHS has declined drastically over the last 18 years. For those less numerate, the pictures show this even more clearly.

The skills required are basic: there’s no multi-variant analysis, no calculation of a p-value, no calculating the skew or kurtosis of a distribution. It’s all very simple and straightforward data extraction, basic computer literacy, Excel skills and simple arithmetic.

It is all basic stuff; something that scientists and skeptics do all the time to check their facts, figures and data, but, it seems, something that homeopaths and homeopathy supporters are incapable of.