QUIZ FEEDBACK: CVD, diabetes and renal disease in elderly people / drug testing in adolescents
This quiz feedback provides an opportunity to revisit the Best Tests March, 2012 articles:
There are now in excess of 25 interactive quizzes available which provide an ongoing opportunity for accumulating CME points.
Testing for CVD, diabetes and renal disease in elderly people
|1. Which of the following statements about CVD risk assessment in elderly people are true?||Your peers||Answer|
|Risk assessment should be stopped for all people aged > 75 years||2%|
|Risk assessment for people aged > 75 years should be calculated using the risk associated with the age 65 – 74 years bracket||83%|
|When to stop CVD risk assessment should be based on the likelihood of ten year survival||25%|
|When to stop CVD risk assessment should take into consideration the patient’s wishes||95%|
|As life expectancy diminishes, it becomes more important to calculate CVD risk||1%|
The majority of identified that, although Framingham CVD risk assessment brackets stop at age 75 years, assessment can continue using the age 65 – 74 years bracket. Life expectancy is continually increasing and a healthy person aged 75 years may live for another 20 years or more, therefore it is important that potentially preventable health conditions, such as CVD, are monitored.
When to stop risk assessment is often a difficult decision to make. Nearly all respondents were aware that the patient’s wishes were an important part of that decision. However, approximately one-quarter also considered that the likelihood of ten year survival was important in making the decision. While ten year survival rate is important, it is a long time-frame to base risk assessment on and can be unpredictable in elderly people. Rather, the decision should be based on patient preferences and beliefs and the presence of severe co-morbidities that are terminal or progressive. And indeed, the vast majority of correspondents were aware that where life expectancy was reduced the importance of assessing CVD risk diminished.
|2. Which of the following statements about lipids and lipid testing are true?||Your peers||Answer|
|Lipid levels naturally increase after age 75 years, regardless of lifestyle factors||6%|
|Lipid testing should occur at least six-monthly in all people aged > 75 years||1%|
|Some research suggests that all-cause mortality in elderly people is highest when total cholesterol levels are lowest||85%|
|There is strong evidence that lipid-lowering treatment for primary prevention of CVD reduces mortality in people aged > 80 years||2%|
|The optimal level of cholesterol is not known in people aged > 80 years||92%|
Lipid levels naturally increase until approximately age 65 years, when they begin to slowly decline in most people. Because of this, lipid testing becomes less important after age 65 years. Most respondents were aware of this and identified answers “a” and “b” as incorrect.
Most respondents were aware of new evidence suggesting that lower lipid levels (< 5.5 mmol/L) may be more harmful than higher levels in older people. The evidence on optimal lipid levels in very elderly people aged over 80 years is conflicting and unclear. There is a lack of evidence of the benefit (in terms of mortality) of lipid-lowering treatments for primary prevention of CVD in people aged over 80 years.
|3. Which of the following statements about testing in people aged over 75 years with diabetes are true?||Your peers||Answer|
|The threshold for diagnosis of diabetes in people aged > 75 years is HbA1c ≥ 55 mmol/mol||16%|
|Glycaemic targets should be more stringent in people aged > 75 years with diabetes (i.e. tighter control)||1%|
|Once HbA1c levels are stable, testing can be three-yearly||6%|
|Microalbuminuria is reversible if detected early||87%|
|ACR is a less robust predictor of nephropathy in elderly people||70%|
While insulin sensitivity does decline with age, and HbA1c levels increase, the threshold for a diagnosis of diabetes remains the same regardless of age (HbA1c > 50 mmol/mol). When to intervene is a somewhat more difficult decision in elderly people, although lifestyle interventions are always appropriate.
Targets for glycaemic control may be less stringently applied in older people, after taking into account their “drugs, diseases and disability”. The regularity of testing should not change in elderly people with diabetes. HbA1c should be investigated at least annually - once per year is sufficient in people with stable, well-controlled diabetes.
Most correspondents correctly indicated that good glyaemic control and management of blood pressure can reverse microalbuminuria, if detected early, regardless of age.
Many respondents were aware that the specificity of ACR declines with age. However, ACR should still be monitored at least annually in elderly people.
|4. Which of the following statements about testing renal function in elderly people are true?||Your peers||Answer|
|An eGFR level < 60 mL/min/1.73m2 is indicative of chronic kidney disease (CKD) in all people regardless of age||18%|
|A decline of > 15% in eGFR over three months should prompt investigation for CKD or other causes in a person aged > 75 years||93%|
|An initial result of a decreased eGFR level in a person aged > 75 years should be repeated within two weeks||84%|
|In people with diabetes an albumin:creatinine ratio > 1.0 mg/mmol indicates clinically significant microalbuminuria||3%|
|Haematuria can be assessed using a urine “dipstick”||91%|
Age has a strong influence on eGFR levels. An eGFR level < 60 mL/min/1.73m2 is the threshold for suspicion of kidney disease in adults, however, in elderly people levels as low as 45 mL/min/1.73m2 do not necessarily indicate kidney disease. Rather, change in eGFR over time and signs and symptoms should be used to indicate whether further assessment is required. A decline in eGFR of greater than 15% over three months is indicative of CKD in older people. An initial low eGFR results in a person aged over 75 years should be repeated within two weeks to monitor rate of decline.
Dipstick testing is sufficient for assessing haematuria, however, further investigation is required for persistent haematuria in elderly people.
Albumin:creatinine ratio (ACR) is the recommended test for assessing the level of microalbuminuria in people with diabetes. A ratio of >2.5 mg/mmol in males and >3.5 mg/mmol in females is clinically significant. Confirmation of microalbuminuria requires three samples taken within six months, with two elevated samples indicating microalbuminuria.
Non-evidential laboratory testing for drug use in adolescents
|5. Which of the following statements about non-evidential urine sample collection are true?||Your peers||Answer|
|Non-evidential drug testing does not require a strict “chain of custody” protocol||89%|
|The patient should wash and dry their hands prior to testing||92%|
|Dipstick analysis of urine should be used to indicate authenticity of the sample||6%|
|A clinician of the same gender as the patient must observe urination||4%|
|A thermometer should be used on the sample to test authenticity||9%|
Most respondents correctly identified that non-evidential drug testing does not require a “chain of custody” protocol. “Chain of custody” is a legal term referring to adherence to a set of procedures, which ensures that urine samples are not contaminated or substituted. Chain of custody is required when testing is conducted for certification, legal or evidential reasons.
Although legal chain of custody is not required for non-evidential purposes, health professionals should take reasonable measures to ensure the urine collection procedure is robust, as it is in the patient’s best interest that there be no suspicion that the sample has been contaminated. Patients should wash and dry their hands as part of the standard urine sample collection procedure. Direct observation of urination is not a requirement, but is likely to provide a strong deterrent to contamination of the sample, if necessary. There are no specifications that the observer must be of the same gender as the patient. An unusually hot or cold sample is an indicator that interference may have occurred, however measurement with a thermometer is not required. Creatinine concentration is reported with urinalysis to confirm sample authenticity.
|6. Which of the following drugs will be detected on a standard preliminary drug screen?||Your peers||Answer|
Most respondents correctly identified that cocaine and heroin are detectable in a standard preliminary drug screen. However, there was less understanding that oxycodone and ecstasy cannot usually be detected in a preliminary screen.
In New Zealand it is standard practice to use an immunological test for the primary screening of urine samples for drug testing. This screen will detect most amphetamines, benzodiazepines, cannabinoids, cocaine and opiates. Opiates, e.g. heroin and codeine, are metabolised into morphine which is detected on the preliminary screen. However, morphine is not a major breakdown product of oxycodone and therefore mild to moderate usage of this drug is unlikely to be detected by a primary drug screen. Ecstasy is not a classical amphetamine as it is a member of the phenethylamine group and depending on the type of immunological reaction used, it may not be detected. Methylphenidate (Ritalin) will also not be detected by standard screens.
Specific detail of suspected drugs that have been misused should be given on the laboratory request form, so appropriate testing can be carried out in addition to the preliminary screen, where necessary. In some cases, the laboratory may perform a gas chromatography/mass spectrometry (GC/MS) analysis specifically for the drug of interest rather than perform a primary screen. GC/MS analysis is frequently performed as a confirmatory test of positive primary screens.
|7. Which of the following statements about interpreting and managing drug test results are true?||Your peers||Answer|
|A dilute sample of urine indicates a high likelihood of drug use||24%|
|Confirmatory testing must always follow a positive preliminary screen in non-evidential drug testing||8%|
|Testing has a low specificity but high sensitivity||32%|
|Drug test results should not be divulged to parents, unless there is prior consent from the adolescent, or the adolescent is deemed not to be “Gillick competent”||86%|
|A positive test result does not always indicate drug misuse||94%|
Almost every respondent was aware that a positive drug test does not always indicate drug misuse and that a confirmatory drug test need not be performed following a positive primary screen, as many patients will admit drug use at this point. The issue of patient confidentiality was also correctly understood by most respondents, who stated that before an adolescent’s test results can be given to their parent, the General Practitioner must have received prior consent from the adolescent or have deemed the adolescent not to be “Gillick competent”.
However, approximately only one-third of respondents were aware that the specificity of drug testing is low. This may have been in part due to ambiguity in the wording of this option. The primary screen used for drug testing has a high sensitivity. However, there are a number of substances that cross-react with the antibodies in the primary screen (see question 8 for examples). Therefore the specificity of the primary screen is not high. Confirmatory testing will confirm the presence of compounds using GC/MS and has high specificity, however, this does not provide any contextual information on the behaviour of the patient. For instance, a positive confirmed test for the presence of opiates does not exclude the possibility that the patient may have consumed food containing poppy seeds.
Normally, urine has a creatinine concentration > 1.75 mmol/L. Creatinine concentrations significantly below this value (especially below 0.5 mmol/L) are likely to have been diluted or contaminated, therefore suggesting the patient has illicitly used drugs. However, a patient may also have a dilute urine sample due to increased fluid intake. It is difficult to ascertain whether or not drug use has taken place, from a dilute sample. False-negative results are possible when a sample is too dilute to interpret.
|8. For some drug classes, a positive test does not always indicate illicit drug use; which of the following substances may produce a positive result in a standard preliminary drug screen?||Your peers||Answer|
|Poppy seed bagels||96%|
Almost all respondents correctly identified that foods containing poppy seeds can potentially result in a false-positive test for opiate use. Most also identified that sertraline can produce false-positive tests for benzodiazepine use. However, only approximately two-thirds of respondents were aware that use of ciprofloxacin (a fluoroquinolone) could also produce a false-positive result for opiates. This question emphasises the importance of the consultation in addressing issues of drug misuse. A drug test result in isolation provides limited clinical information. A concise history is required to exclude any possible sources of false-positive results prior to testing. A drug test also provides no contextual information and a psychosocial welfare assessment, e.g. HEEADSSS, SACS or CRAFT, should be performed on all adolescents suspected of substance misuse.