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Lipid Testing for People with Cardiovascular Disease

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Background

Lipid testing is a key component of cardiovascular risk assessment and modification. We hope this new ‘Express Audit’ will help you reflect on your use of these important tests. If you identify a gap in your practice, we would encourage you to work through the continuous quality improvement cycle outlined on the back page. This ‘Express Audit’ is endorsed by the RNZCGP as a CQI activity. This means you can claim MOPs points for each cycle of this audit that you complete. Please note the audit is now out of date and no longer available.

Nitrolingual spray is used almost exclusively for the management of angina. People with angina have a five year cardiovascular risk of >20% and will benefit from lipid modification no matter what the levels. It is recommended these people have annual cardiovascular risk assessment including annual fasting lipid testing.

Graph one shows the number of people nationally who were dispensed Nitrolingual spray (yellow line) and the number of these people who also had a lipid test during this time period (dark blue line). There appears to be a significant gap representing people who were on Nitrolingual spray but do not have lipid testing.

Graph two shows the rates of lipid testing for males and females on Nitrolingual spray.

These graphs suggest three things to us:

  1. Approximately 30% of people on Nitrolingual spray are not receiving annual lipid testing.
  2. There is a small but consistent difference between lipid testing rates between males and females, even though all already have ischaemic heart disease and are at high risk.
  3. The rate of lipid testing falls off significantly over the age of 75 years.The decrease in testing over the age of 75 years demonstrates the pragmatic approach GPs take. There is little evidence for lipid testing above this age and it appears that the combined wisdom of our GPs is to consider discontinuing testing above this age.

Graph three shows national lipid testing by ethnicity as a percentage of the census population for whom cardiovascular (CV) risk assessment is recommended (see notes). We do not know what percentage of the population ideally should have been tested during this limited time-period, but we can compare testing between ethnic groups.
The bar graph shows that Māori get significantly less testing than other ethnic groups despite the fact that Māori are at high risk of cardiovascular disease and are 2.8 times more likely to die of ischaemic heart disease than non-Māori.

Graph four shows national lipid testing for people that are on Nitrolingual spray. As the recommendation is to test these people annually, we would expect the percentage to be close to 100%. This is clearly not the case and we can again see the marked differences between the ethnicities.
The blue bar on the graph shows lipid testing for people between the age of 45 and 75 for whom you prescribed Nitrolingual spray. People were assigned as your patients if they received Nitrolingual spray on your prescription in the time-period, we then checked to see if they had had a lipid test performed by any clinician during that same time-period.

88 % of your patients on Nitrolingual spray had been tested.

Graph five shows the percentage of people nationally on Nitrolingual spray also prescribed statins. People on Nitrolingual spray already have ischaemic heart disease and modifying their lipids is likely to be beneficial no matter what the level. We would expect that most would benefit from being on a statin.
The blue bar on the graph shows statin prescribing for people between the age of 45 and 75 for whom you prescribed Nitrolingual spray. People were assigned as your patients if they received Nitrolingual spray on your prescription in the time-period.

85 % of your patients on Nitrolingual spray had been prescribed a statin.

Notes:
Cardiovascular risk assessment is recommended for all European males 45 years or older, European females 55 years or older, Māori and Pacific Peoples males 35 years or older, Māori and Pacific Peoples females 45 years and older, Asians 45 years or older.
Time Period 1 March 2006 - 31 May 2007.
Patients were assigned to you if they were dispensed a nitrolingual pump spray on a prescription with your NZMC number within the time period 1 June 2005 to 31 May 2007.
Lipid testing or statin prescriptions may have been supplied by other prescribers.
Data has been excluded where the NZMC or NHI number was not recorded.
Graphs three to five depict ages ≥ 45 except: European - Female(≥55); Māori and Pacific Peoples - Male (≥35). Please note the upper age limit for graphs four and five is 75 years.
Any Patients that died within the time period were excluded.
Population data: Estimated National Ethnic Population by Age and Sex as at 30 June 2006 retrieved October 26, 2007 from http://www.stats.govt.nz/tables/population-estimates.htm