Huge rise in gout cases

'Disease of kings' is on the rise as more people get gout due to rising rates of obesity, according to the Daily Mail.

Gout is a condition that causes pain and swelling in the joints. It often affects the big toe but can affect larger joints such as the knee, and is caused by a build-up of uric acid crystals (a waste product) in the joint.

Historically, gout was associated with fine living and dining, making it the ‘disease of kings’. Henry VIII is known to have been crippled by gout in his later years.

In modern England, where eating too much wild swan is no longer a problem, gout is linked to obesity, excessive alcohol consumption and taking a type of medication known as diuretics, which are used in the treatment of high blood pressure.

The headlines are based on a recent study that looked at the number of hospital admissions of people with gout over a 10-year period (1999-2009) in England compared to New Zealand.

The researchers report that, over the course of the 10 years the number of admissions for gout increased by 5.5% each year in New Zealand and 7.2% per year in England. They say that, over the course of a decade, this resulted in a massive rise in admissions in England, at an 86.6% increase.

The researchers found that many of the gout cases in New Zealand were associated with cardiovascular diseases. As obesity is known to increase the risk of developing these conditions, it is fairly reasonable to assume that the current obesity epidemic, both in this country and in New Zealand, could be at least partially responsible for this sharp rise in gout cases. However, this cannot be directly proven by the statistics obtained by the researchers.

Methods that may help you to reduce your risk of developing gout include maintaining a healthy weight by exercising and eating a healthy diet.

Where did the story come from?

The study was carried out by researchers from the University of Otago, New Zealand, and was funded by the same university. It was published in the peer-reviewed medical journal Rheumatology.

The headline in The Daily Telegraph – "Gout cases double in a decade" – is probably most representative as it simply reports the figures, rather than directly attributing the rise to increasing obesity levels as some other media sources have done. The researchers do discuss the possibility that the rise may be linked to the rise in obesity, as well as obesity-associated conditions, such as high blood pressure and diabetes. But they are careful to point out that this study does not provide direct evidence of a causal effect between a rise in obesity and a rise in gout cases, and that further research is warranted.

The media also reinforce the idea that gout is a rich man’s disease, which it is not. In the past gout may have been confined mainly to portly Victorian gentlemen who ate and drank too much at their dining club. Now most cases of gout occur in working- and middle-class people of working age.

In addition, gout has many causes other than obesity and alcohol consumption, such as the use of certain medications or eating foods that are rich in a substance called purines. Purines are found in beef, pork and seafoods. In some cases certain people don’t excrete uric acid from their bodies as well as others, and it builds up. For this reason, gout is known to run in families.

What kind of research was this?

This was a time trend study designed to look at the number of hospital admissions of people with gout over a 10-year period in New Zealand.

Two types of admissions were assessed:

• admissions where gout was the direct cause of admission, and
• admissions where gout was not the direct cause but it was complicating whatever illness the person was being admitted for (for example, people with gout are often also affected by conditions such as high blood pressure and kidney disease)

The researchers looked at demographic details of the people admitted and the other co-existing medical conditions. The researchers then compared their data with admission data collected by the NHS within the same time period. They picked the two countries for comparison as previous studies are said to have observed that New Zealand has among the highest reported levels of gout, while England has lower rates. In particular, they wanted to see whether the medical conditions associated with gout (comorbidities) were similar in both countries.

This type of study can provide us with useful information on how the number of admissions due to certain medical conditions has changed over time, but it can do no more than that. It can’t tell us what has caused any change in disease rates.

What did the research involve?

The researchers used data from the New Zealand Ministry of Health, which collects information on all non-private hospital admissions in the country. They extracted data on all patients admitted between July 1999 and June 2009 where gout was recorded as the primary discharge code (meaning that gout had been the reason for their admission) or where gout was a secondary code (meaning that gout was complicating whatever medical condition the person had been admitted for). 

For each case they also obtained data on:

• age
• sex
• ethnicity
• socio-economic status
• admission date
• length of hospital stay
• other co-existing or complicating medical conditions

They also linked to the New Zealand death registry.

The researchers also analysed similar publicly available information on all admissions associated with gout in the NHS in England between April 1999 and March 2009.

What were the basic results?

Over the 10-year period in New Zealand there were 10,241 admissions directly due to gout, and 34,318 admissions where gout was not the direct cause of admission but was complicating another illness. Men made up about three-quarters of those admitted with gout. There was also a higher representation of those of Maori or a Pacific Island ethnic origin than present in the general population.

Generally, there were some differences in the co-existing medical illness of those admitted directly due to gout and where gout was complicating the admission.

Among those where gout was the direct cause of admission:

• 19% had high blood pressure
• 20% had diabetes
• 14% had cardiovascular disease
• 16% had chronic kidney disease
• 14% had at least one co-existing infection

Among those for whom gout was complicating their admission:

• 39% had high blood pressure
• 27% had diabetes
• 39% had cardiovascular disease
• 27% had chronic kidney disease
• 38% had at least one co-existing infection

People in this second group, who had gout but were admitted for other causes, also tended to have poorer survival outlook over the following five years, compared with those admitted specifically for gout.

During the same time period in England there were 32,741 admissions due to gout (the data did not specify whether this was direct cause or not). Over the 10-year period in New Zealand the number of admissions due to gout rose by 5.5% per year, compared with 7.2% per year in England. Over the course of a decade this amounted to a total rise of 86.6% increase of gout admission cases in England.

When taking into account total population numbers, the number of admissions due to gout was still higher in New Zealand. The 2008/09 rate was 27 per 100,000 population compared with nine per 100,000 population in England.

How did the researchers interpret the results?

The researchers conclude that hospital admissions associated with gout are rising in both New Zealand and England, and their data show that those admitted in New Zealand have a high rate of co-existing illness and re-admission.

Conclusion

This study is valuable in reportedly being one of the first to examine the number of hospital admissions associated with gout from across an entire country and to look at this over a long period of time. The research demonstrates that the number of admissions where people have gout has risen over the 10-year period in both New Zealand and England.

In New Zealand, the researchers observed that several co-existing illnesses – predominantly cardiovascular diseases – are associated with gout. As these diseases are associated with obesity, it is a reasonable theory that rising obesity levels could be associated with the increase in gout; however, this study cannot prove this theory.

As the researchers acknowledge, obesity is often not documented in medical records and, therefore, cannot be implicated as a causative factor based on this type of analysis alone. One possible reason for this is that doctors may be worried that recording the fact that a patient is obese may cause offence at a later date if the patient requests access to their medical records.

The study did not actually report what proportion of individuals admitted with gout were recorded as being overweight or obese.

We can say even less about what may be responsible for the rise in hospital admissions associated with gout in England, as more limited data were available for England. The data analysed simply recorded the number of admissions where gout was listed – they did not report on co-existing medical diseases for people in England.

All we can say for England is that admissions either directly for, or associated with, gout rose by 5.5% per year between 1999 and 2009. Why this happened, we cannot say. What we can say is that gout is certainly not a ‘disease of the past’.