Thursday December 11 2008
The study looked at 57,615 patients diagnosed with panic attacks
People who suffer panic attacks are a third more likely to have a heart attack, claims The Daily Telegraph. The story comes from new research into the complex relationship between the symptoms of panic attacks and heart attacks, which can often be similar. The newspaper also claimed that stress itself might also cause damage to the heart or arteries.
This study looked at 57, 615 UK patients who had been diagnosed as having panic attacks. It found that those under 50 years of age were 38% more likely to suffer a heart attack than similar patients who did not have panic attacks. There was no significant difference in risk in older age groups.
However, the risk of dying from heart disease for panic attack sufferers was 24% less than among non-sufferers, possibly because they saw their doctor more often.
As the researchers acknowledge, the design and limitations of this study need to be considered when interpreting its results. While it may be that panic attacks and heart problems are linked in some way, these results might arise from heart problems being misdiagnosed as panic attacks.
Where did the story come from?
Dr Kate Walters and colleagues from University College London, UK carried out this research. It was funded by the Medical Research Council and published in the peer-reviewed European Heart Journal.
What kind of scientific study was this?
This cohort study investigated the risk of coronary heart disease (CHD), heart attack and deaths from heart disease in patients with panic attacks or panic disorder. It used data from a registry of patients seen in primary care, the General Practice Research Database (GPRD), which pooled data from 650 GP practices.
The researchers selected adults older than 16 years with panic attacks (or panic disorder) who were entered into the GPDR between 1990 and 2002: a total of 57,615 people. People with a previous recorded diagnosis of heart disease or panic disorder prior to entry into the study were excluded, as were patients who had less than six months of reliable medical records.
These patients were matched to a random sample of 347,039 people who had no record of either condition. For each case, they chose six patients of the same sex and age group (in 10-year bands) who had been registered for the study at about the same time. This group was used as a comparison, or control group, for the patients.
The researchers followed everyone until the end of the study or until they left their GP’s practice, to identify those who developed CHD, had a new heart attack or died from heart disease (CHD-related).
Using recognised statistical methods, the researchers adjusted for age, sex, deprivation, heart disease risk factors (such as smoking and blood pressure), psychiatric conditions and the number of prescribed medication. This was to ensure that there were no other factors that varied between the groups and influence any effect seen.
What were the results of the study?
For people under 50 years of age there was a higher rate of new heart attacks after being diagnosed with panic attacks/disorder for the first time compared to those without panic attacks This group had a 38% increase in their risk of heart attack, which was statistically significant (Hazard ratio [HR] 1.38, 95% CI 1.06 to 1.79).
There was no significant difference in new heart attack rate in the older age groups following a diagnosis of panic attacks/disorder when compared to the control group (HR 0.92, 95% CI 0.82–1.03). There was also a higher rate of new onset CHD for all ages, especially in those under 50 years.
While the risk of a heart attack went up following a first diagnosis of panic attacks, the risk of death from a heart attack was significantly reduced, by 24% (HR 0.76, 95% CI 0.66–0.88).
What interpretations did the researchers draw from these results?
The researchers conclude that new onsets of panic attacks or panic disorder were linked to an increased chance of subsequent coronary heart disease or heart attack in people below 50 years of age. This increased risk was much lower in people over 50. Both age groups had a slightly reduced hazard of CHD-related death.
They say this may be due to CHD being initially misdiagnosed as panic attacks or that there is an underlying increased risk of CHD with panic attacks or disorder in younger people.
What does the NHS Knowledge Service make of this study?
The researchers make some comments about their study. They say that:
- Previous research has found that the diagnosis of heart attacks and heart disease in the GDPR registry compares well with hospital records. However, there were no studies to test how accurate the diagnosis of panic attacks/disorder in the registry was and diagnostic criteria was not discussed in the report.
- The overall numbers of people with a diagnosis of panic disorder in their sample was lower than expected and the researchers thought this might be because some people may not report their symptoms to their GP, or that GPs might not recognise or record the symptoms as a panic attacks/disorder.
- There was only a limited amount of information on some patients’ socio-economic background. The researchers therefore used deprivation scores for the area around some patients’ GP practices as the best available alternative for individual deprivation.
- Other data collected was limited or incomplete, such as records on smoking or patient ethnicity. The lack of complete data on, for example, smoking may be an important source of bias because if smoking were linked with both panic attacks and heart attack it may explain the link shown.
- Importantly, the researchers reanalysed their data to take into account the missing data on smoking and this had no impact on their models.
As the researchers say, their results should be interpreted with caution, particularly as they were unable to adjust for the fact that some GPs might tend to under-report both heart disease and panic disorder, and that this could have influenced the link.
There is also a difference in the direction of effect for two of the outcomes - the good and bad news. Overall, this study had several advantages as a result of being large and assessing outcomes after the diagnosis of panic attack. This means it is possible to have greater certainty that people were not simply panicking because they already knew or had just found out that they had heart disease.
However, the limitations acknowledged by the researchers and the observational nature of the study mean that it is not possible yet to be sure if there was any clinical misdiagnosis of heart disease as panic attacks, or if there truly is an underlying increased risk of heart disease for those with panic attacks.
Sir Muir Gray adds...
The effects of stress are still probably underestimated and the mind does affect the body dramatically.