U3A Talk

This is a talk on life as well as on common medical controversies.
People are generally well meaning.
Treat others as we would like ourselves to be treated is a motto that most if us work by.
So where does it go wrong?”
Well I guess we all like to be treated in different ways.

I like to think on the alternatives in life, in the choices we make, why we make them and the consequences both obvious and hidden.

Diabetes
Coeliac disease
Vaccinations.
Screening tests.
The big ones here are Prostate Cancer, Breast Cancer and Bowel Cancer. Why screen at all?

A silly question which carries a sting in the tale.

To detect cancer, and other diseases early enough to be able to do something about them.
Disease exist in our community that develop over time and cause serious health problems.
Tests exist to detect these diseases.
Simple enough.
It has nothing to do with preventing such diseases.
Having a screening test does absolutely nothing to prevent a disease occurring or even worse being present when you do the procedure and being missed.

Who has screening tests. People at risk.

Family History . Population History. Occupational History , Exposure History.

A screening test has to be useful, It has to  have a high sensitivity and high specificity. This means that it is able to detect problems early enough [sensitivity], and accurately enough [specificity].

It has to diagnose conditions that are dangerous, reasonably common and hopefully treatable without causing problems of it’s own worse that what one is trying to treat, in other words it has to be safe.

Screening can by done by endoscopy, faecal and urine sampling, Blood tests and Radiological procedures such as X-Ray, CT , Bone scan and MRI to mention a few.

Pitfalls of testing.

Cost , the equipment is all there  but some are very expensive. New tests in particular. Cheapest but still not cheap are the Urine testing for sugar protein and blood

Time, Some tests like 24 hour ECG’s and bone scans can take days to do

Patients often have limited time themselves to do the test in.

Discomfort

Danger

Loss of results

Wrong results

Statistical use of the results.

Endoscopy, looking inside the body through a tube, is a good way of detecting cancers. Lung, throat, Stomach, bladder  and bowel cancer can be detected this way.

Who here volunteers to have a colonoscopy every 6 months? or a bronchoscopy.

Questions

Would you have all of them every 5 years? What would be a good age to start.

Not many , Reasons  discomfort, embarrassment, time , risk

Having a procedure often involves having an anaesthetic, The risk of dying from an anaesthetic increases with age and other medical conditions but can occur in healthy young people as well. Somewhere between 1 in 5,00 to 1 in 10,000. As well as the risk of the procedure itself. Perforation of the bowel and  bladder, rupture of the oesophagus, damage to the vocal cords, aspiration and pneumonia, Urethral stricture with a urethroscopy .

wrong diagnosis, no diagnosis, missed diagnosis and lost specimen.

Import of the result and use of statistics. This is one that I have great difficulty in understanding.

Say that a mammogram will diagnose a breast cancer with 95% accuracy.

You have a patient who comes to you with a positive result from a screening procedure.

What should you tell her. As the patient if you are told it has a 95% accuracy what does this mean.

Murky waters lie ahead. The false positive paradox is a statistical result where false positive tests are more probable than true positive tests, occurring when the overall population has a low incidence of a condition and the incidence rate is lower than the false positive rate. When the incidence, the proportion of those who have a given condition, is lower than the test’s false positive rate, even tests that have a very low chance of giving a false positive in an individual case will give more false than true positives overall.[2] So, in a society with very few infected people—fewer proportionately than the test gives false positives—there will actually be more who test positive for a disease incorrectly and don’t have it than those who test positive accurately and do. The paradox has surprised many

Low-incidence population

Number
of people
Infected Uninfected Total
Test
positive
20
(true positive)
49
(false positive)
69
Test
negative
0
(false negative)
931
(true negative)
931
Total 20 980 1000

Now consider the same test applied to population B, in which only 2% is infected. The expected outcome of 1000 tests on population B would be:Infected and test indicates disease (true positive)1000 × 2/100 = 20 people would receive a true positiveUninfected and test indicates disease (false positive)1000 × 100 – 2/100 × 0.05 = 49 people would receive a false positiveThe remaining 931 tests are correctly negative.

In population B, only 20 of the 69 total people with a positive test result are actually infected. So, the probability of actually being infected after one is told that one is infected is only 29% (20/20 + 49) for a test that otherwise appears to be “95% accurate”.

A tester with experience of group A might find it a paradox that in group B, a result that had usually correctly indicated infection is now usually a false positive. The confusion of the posterior probability of infection with the prior probability of receiving a false positive is a natural error after receiving a life-threatening test result.

As breast cancer in the general female population is a relatively low incidence disease the outcome of a false pasotive is quote high.

Herein another risk, traumatising people with false positives and equivocal results, one does not like to rule out cancer conclusively if some doubt is present leads to up to 15% of women who have a screening mammogram having to undergo further procedures , usually invasive biopsies  with pain discomfort, bruising and rarely infection.

Not to mention the 5% who have a false negative, also not as common as it sounds.

Finally  Cancers are incredibly small, incredibly fast growing and have usually been present for 6-18 months before getting big enough to be detected. So one may have a bowel or breast cancer present at the time of screening, have it missed due to its size and present with a large cancer 6 months later.

Finally removal of the cancer does not guarantee that the cancer has been successfully treated. Cancers can spread [metastasize] before removal. Melanoma is an example.

In the other hand BCC usually grows locally only but very aggressively, Some poor souls it does metastasize. SCC  has a slightly higher spread rate than BCC which is why it needs removal and follow up.

 

Prostate Cancer is an enigma which is treated in an ageist and sexist manner by most people and the medical profession. It has none of the media appeal of breast cancer,  the young mother cut down in her prime with dependent children and husband.

Instead an older man has a blood test at the insistence of his wife and gets told his PSA is up.  Still the hope of a wrong diagnosis. Multiple other causes. He may have an infected prostate, very high reading 20+ , treatable with antibiotics. He may have BPH [benign prostatic hyperplasia] an example of the word benign not really meaning what you think it does. At least it is not cancer and after 15 hours of agony not being able to pass urine a catheter is inserted by a first year resident, hopefully in the right place with no perforation and one is on the way to a TURP  or onion peeling from the inside with the risk of loss of sexual function, not that it matters for an old guy anyway.

Next he has a trans rectal biopsy with 12 needles taking samples then he is told the bad news.

Bad news? We are doing nothing for you. Most men with prostate cancer are so old they die with it not because of it. Prostate cancers can be very slow growing [Which type have I got? We don’t know] Your life span is to short  to worry about it. The treatments cause loss of sexual function, baldness and you will go blind.

Only joking.

The facts are that prostate cancer is treatable, One can have surgery, radiotherapy or a combination.

Prostate cancer does spread rather early so  prevent developing cancer or to
Males generally get cancer later than females

I would like to present an over view of the screening dilemma.

I will reference my talk to certain illnesses and conditions that are common in the community and a few that are not. Along the way I will mention several misconceptions with these conditions. I welcome relevent questions but will deal with most in the breaks or afterwards.

Medicine is concerned with the health of individuals first and  then with health of populations. It consists of both diagnosis and treatment of medical conditions. Originally these were of the body but those of the psyche then followed. As new treatments and medications were developed medicine became an enlarging field with more expectations of keeping people healthy.

Means of diagnosis improved. At first these were only applied to people with illnesses, but then the ability to look for problems ahead of time became apparent and screening was born.

Screening is a form of diagnosis that came late to medicine. Tests on urine for protein and blood were possible. Blood tests began being used at the start of the 19th century and X-Rays were developed.

Progress was slow so much that the routine testing strips we know use routinely with 10 tests on were still a 2 strip novelty 40 years ago ..

CXRays for TB detection were among the first general screening projects undertaken.

This dreaded disease, still present today, was reduced a hundred fold with detection treatment and isolation. Screening was abolished in the 1970’s in Australia. for 3 reasons which are still valid today. Cost, Radiation exposure [side effects] and near elimination of the condition. One funny twist of fate due to litigation and over investigation a large percentage of the population still have CXR’s for other reasons which equate to a de facto screening program.

The modern health problems are those of living longer, diabetes cancer and heart disease [stroke]. These conditions all increase with age and all reduce life expectancy greatly. They have an enormous impact at any time but more so when the sufferers are young.

Ao to screening.

The ideal screening test is something non invasive, very reliable easy to do and producing a treatment outcome beneficial to the patient.

Bowel Cancer.

A sample of poo, well 2 or 3 actually a day apart preferably after avoiding meat in the diet an

 

 

 

 

 

 

climate

I did say “Only 37 of 58 sources list raw data”.
“37 of 58 represents the fraction of data sets”,
yes that is exactly what I said.

” not the fraction of raw data,”
I did not make that claim.

“You have denied for years that there are more than 5000 stations in the world ”

I have denied the number of active stations in the world.
There is a difference. Take
“International Surface Temperature Initiative (ISTI), . This release in its recommended form consists of over 30 000 individual station records, some of which extend over the past 300 years.”
this gives 30 thousand stations which are mostly inactive or extinct.
Station locations existing within the last 300 years with at least 1 month of data are used in GHCN-M version 3 (a).
Station locations during the periods 1871–1900 (b), 1931–1960 (c), 1961–1990 (d), and 1991–2013 (e) are also shown.

Or take
(GHCN-M) dataset in 1992, more than 6000 stations. A second version of GHCN-M, containing 7280 stations in 1997 in 2011, a third version of GHCN-M.
which says makes Routine updates for about 2000 stations are made on a daily basis.

Or
NASA’s GISS dataset 6000 stations.
A bit of tight squeeze as  Since version 2, GHCN-M has been a major component in the GISS data set. A bit hard to fit 7280 stations into 6000 but as only 2000 are active I guess you can ignore the rest.

Then
the United Kingdom produced a first release of its CRUTEM product in the late 1980s. Today, a global dataset of over 6000 stations is still maintained in its fourth iteration. Since it also includes GHCN I guess it might have only 2000 active stations as well.

mathematically 2000active stations in the world seems to confirm  my position that “You have denied for years that there are more than 5000 stations in the world ”
Today, GHCN-D provides daily maximum and minimum temperature for nearly 30 000 stations. Although more stations exist on the daily scale
Given the historical nature of data creation, sharing, and rescue, there are many cases where a single station exists in multiple data sources.
the duplicate records do not necessarily have identical temperature values for the same station even though they are based upon the same fundamental measurements.
There are 194,367 station records used
Although the preference is to have data as raw as possible, there are times where such data do not exist, or have not been provided to the databank. Therefore pre-processed data are accepted
GHCN-D was selected to be the highest priority, or target dataset, and the monthly dataset derived from it is the starting point for the merge process. GHCN-D is regularly reconstructed, usually every weekend, from its 25-plus data sources to ensure it is generally in sync with its growing list of constituent sources
the U.S.-based Cooperative Observer Program (COOP) Summary of the Day data set. These sources provide data for more than 2500 stations worldwide, and they remain the primary sources for updates to version 3.
[25] CLIMAT bulletins transmitted via the Global Telecommunication System (GTS) provide data each month for approximately 1400 GHCN-M stations in more than 125 countries and territories.
Locations of the approximately 2300 GHCN-M stations for which data are routinely available.

Bill

Dr Brian Cluney

Stuart Park Surgery, 1/5 Westralia St Stuart Park.

Dear Brian,

I am the older brother of William [Bill] and live in Shepparton, Victoria, semi retired GP. Bill lives with his partner Janine in an upstairs house at Tong Luck St, Rapid Creek and attends your practice. He has been having a lot of difficulty with back and leg pain in the last 6 months which has been causing a lot of concern to him and to his 92 year old mother, Nancy, who currently lives in the Gold Coast but had been a Darwin resident for 55 years.

Bill has had 3 major accidents in his life. At 17 yo in Adelaide he was hit by a car and thrown onto the windscreen. Not sure if knocked out or severity of other injuries.

His major accident was in 1982 when his father rolled a Ute on the way to Broome, WA throwing Bill out. He was flown to Royal Perth Hospital deeply unconscious and remained in a coma for 6 weeks with head injuries. He slowly recovered but had severe right sided weakness of his  arm and leg  needing prolonged rehabilitation. He was also left with permanent double vision. The main problem however was altered personality [? frontal lobe]  and a marked decrease in mental cognition.

After several years he returned to work as a wharfie with his father on the Darwin Wharf , and also as a health and safety officer. Some years after that ??1987 he had his third accident when he fell 22 feet down a ship’s hold. The result of this was severe bilateral torn rotator cuffs which put an end to his wharf career and caused him to be in severe pain for quite a few years. He did see surgeons at Darwin Hospital, not sure of he had operations.

He tried to work spasmodically since then but has basically been unemployed reliant on a pension set up by his mother from his motor car accident .

Bill is very hard to get history out of because of his poor memory. He tends to make light of his problems due to a combination of poor memory and possibly a frontal lobe injury affect. He is difficult to treat because he forgets instructions and lacks motivation. Worse he has a strong belief in alternative and unusual medicine and is immune to reason.

Despite this he has an easygoing personality and is always willing to help out others. I have left him to his own devices in the past as his mother and sister, Jennifer Lee, had mainly been involved with his supervision.

The problem currently is repeated attacks of severe leg and back pain which make it very difficult to get up and down the stairs at home for the last 6 months. I saw the CT back you arranged which showed the L5 disc protrusion and  nerve root possible compression and the funny little comment re bubbles in the L3/4 canal.

He went to the Darwin Hospital Casualty last night [Sunday]  with right upper inner leg pain down to the knee. The doctor on call tried to get him admitted but there were no neurological symptoms and the consultant opted for referral to physio at the Hospital and a non urgent Orthopaedic review which could take months. He suggested that I contact you to ask if you could also refer him to the Orthopaedic unit as this might help speed assessment up.

Also a care plan for physiotherapy if it is helping.

I realise the problems inherent in managing back pain, it is Australia wide. Bill is 8 years younger and Dad had both prostatomegaly and bowel cancer late in life. Bill is only 57. Bill does not normally complain of pain and incapacity without reason and it is a worry that this has been going so long. There may be some arthritis from his accidents, there may be a disc compression problem if he has neurological symptoms and the doctor at Darwin Hospital did say something about some narrowing of the right hip joint.

I wondered  if a PSA and a bone scan might help rule out any other causes if his back pain continues and you feel they are worth doing. I hope to get up to Darwin in May to assess his situation and hope we can speak then.