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2016 November 25

Heart risk

Filed under: Uncategorized — gasstationwithoutpumps @ 18:11
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My 90-year-old father recently needed several stents installed, because his coronary arteries were 85–95% blocked. This came as a bit of a shock to the family, as we had thought his heart was in good shape (aside from needing a pacemaker). So I’ve been thinking a bit about my own risk of coronary vascular disease (CVD), especially since I have hereditary high cholesterol (from my Mom’s side of the family).

Like any modern academic, I turned to the web for more information. There are many calculators on the web for computing one’s risk of CVD, almost all claiming to be based on the Framingham study of heart health. Unfortunately, they disagree enormously (by  a factor of 2) on what my risk is.

I used the following statistics for all site: age 62, male, cholesterol 161 mg/dL=4.16mmol/L, HDL 43 mg/dL=1.11mmol/L, triglycerides 90 mg/dL=1.016 mmol/L, BP134/83mmHg, height 5’11” (180cm), weight 163 lbs(74 kg), race white, no treatment for blood pressure, non-smoker, and no diabetes, though these numbers are not all from the same day, and I’m doubtful of the blood-pressure reading, as it was done with a cheap home cuff that I don’t believe handles my low heart rate well.  (When I’ve had oscillometric and auditory measurements made at nearly the same time, the oscillometric ones have been substantially higher.)

I got the following risks of CVD in the next 10 years:

Site Risk
 http://www.mdcalc.com/framingham-coronary-heart-disease-risk-score/  9.7%
 https://www.uptodate.com/contents/calculator-cardiovascular-risk-assessment-10-year-men-patient-education  10%
 https://www.framinghamheartstudy.org/risk-functions/cardiovascular-disease/10-year-risk.php#  10% (using lipids), 17.9% (using BMI)
 http://www.cvriskcalculator.com/  10.1% (heart attack or stroke)
 http://tools.acc.org/ASCVD-Risk-Estimator/  10.1%
 http://reference.medscape.com/calculator/aac-aha-cardiovascular-risk-ascvd  10.1%
 http://medcalc3000.com/ACCAHA2013.htm  10.1%
 http://www.mayoclinic.org/diseases-conditions/heart-disease/in-depth/heart-disease-risk/itt-20084942 10.1%
 https://qrisk.org/2016/index.php  11.4%
 http://chd.bestsciencemedicine.com/calc2.html  15.4% (Framingham), 11.6% (Qrisk2), 10.3% (ACC/AHA ASCVD)
 http://patient.info/doctor/cardiovascular-risk-calculator  12% (CHD), 5% (MI), 3% (CHD death), 3% (stroke), 18% (**CVD),  4% (**CVD death), 14% (JBS CVS Risk)
 http://www.medcalc.com/heartrisk.html  13%
http://reference.medscape.com/calculator/framingham-cardiovascular-disease-risk  15.0%
 https://www.cvdriskchecksecure.com/FraminghamRiskScoreResults.aspx  18.4%

I’ll have to ask my doctor whether it is worth getting a high-sensitivity C-Reactive Protein (hsCRP) test for inflammation to use one of the risk calculators that takes inflammation into account.

The risks are about normal for my age, but I’d like to reduce them if I can.  I’m already on statins (and have been for 25 years) and 81mg aspirin (self-prescribed), I already get about 150 minutes a week of moderate exercise, and I’ve been controlling my weight (though I’ve put on 4 lbs in the past year that I’d like to get rid of).  I’m not sure how much more I can reduce the risk.

2015 March 31

Third weight-loss progress report

Filed under: Uncategorized — gasstationwithoutpumps @ 20:22
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In 2015 New Year’s resolution , I said that I want to lose 10–15 pounds by June 2015. In Weight-loss progress report and Second weight-loss progress report, I provided a monthly updates.

For March, I continued the same diet and exercise as in January and February, except for March 20–29, when I had Spring “break” (a huge pile of grading, rewriting the book for my applied electronics class, and other administrative and course preparation tasks).  I wasn’t cycling up to campus everyday, so my average exercise dropped to 4.31 miles/day of bicycling. Also, my son, a freshman at UCSB, had his Spring break at the same time, and so came home for the break.  Because he is very thin (as I was at a corresponding age), his mother served a number of comfort foods while he was here, to encourage hearty eating.  So I put on a little weight and am trying to lose it again.

A simple linear extrapolation would have me reaching the upper end of my target range by 2015 Apr 23, but an exponential decay predicts that I won't reach it until June 13.

A simple linear extrapolation would have me reaching the upper end of my target range by 2015 Apr 23, but an exponential decay predicts that I won’t reach it until June 13.

I am at the lowest weight I’ve been since I bought the scale in 2011 and started recording my weight.  Although I was losing 1.24 lbs/week in January and 0.74 lbs/week in February, I only lost 0.52 lbs/week in March.  Because of this progressive slowdown, I fit an exponential decay to my weight loss, as well as the simpler linear fit.  The exponential predicts an eventual minimum weight of 157 lbs with a decay time constant of 89 days. This asymptotic weight is comfortably within my target range—but if the exponential holds up, then it will take me longer than I had originally expected even to get within my target range.

During break I had a checkup with my physician, who thinks my target weight range is fine, but she’d be happy even if I just managed to maintain my current weight. Interestingly, my cholesterol was at the lowest level since I’ve had it measured (starting in 1989), and the desirable HDL was actually up.  Unfortunately, I did not check the cholesterol levels before starting my diet, so I don’t know whether the low levels are due to the diet or to the rather high levels of atorvastatin (60mg/day) that I’ve been taking for the past 2 years.  In any case, I’m cutting back to 40mg of atorvastatin a day, and I will check my cholesterol levels again over the summer.

 

2014 January 23

Pill prices are not uniform

Filed under: Uncategorized — gasstationwithoutpumps @ 10:44
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This year UC eliminated the health care plan that I’ve been using for the past several years, and the closest similar plan was quite expensive.  I decided to switch to a low-cost plan that has a high deductible, which means that I’ll be paying cash for my prescriptions and doctor visits this year, at least until I reach the deductible (which probably won’t happen—unless I have a major bike accident or someone in the family gets seriously ill).

I take generic atorvastatin, a very cheap drug, on a daily basis for controlling cholesterol. I decided to check whether I should continue with the pharmacy I’ve been using (the closest one) or look for a cheaper one.  Under the previous insurance plan, I could select pharmacies for convenience, since my co-pay was the same no matter what.  I checked online, and found that Consumer Reports had found a big difference between pharmacies for generic atorvastatin, so I called both my current pharmacy and Costco (the one that Consumer Reports had found cheapest).

If I stay with the CVS I’ve been using, my atorvastatin would cost me $9.40 a day.  At Costco, it would be 77¢ a day (both based on 100-pill purchases of both 2omg and 40mg pills and no Costco card or other discounts). I had expected some difference in price, but not a 12-to-1 difference!

If I used a pill splitter, I could reduce the costs to $7.05 a day at CVS or 61¢ a day at Costco, but the hassle of splitting pills is not worth 16¢ a day.  Needless to say, I’ve asked my doctor to switch my prescription to Costco.

2012 March 28

Non–HDL cholesterol level and statins

Filed under: Uncategorized — gasstationwithoutpumps @ 18:59
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A meta-analysis was just published in the Journal of the American Medical Association, Association of LDL Cholesterol, Non–HDL Cholesterol, and Apolipoprotein B Levels With Risk of Cardiovascular Events Among Patients Treated With Statins, March 28, 2012, Boekholdt et al. 307 (12): 1302 — JAMA, that suggests setting statin dosage by the non-HDL cholesterol, rather than LDL, as is more commonly done.

They looked at a number of studies and tried to determine the effect (in terms of increase in cardiovascular “events” per standard deviation change) for three measures: LDL cholesterol, non-HDL cholesterol, and apolipoprotein B.  They found that non-HDL cholesterol was the best predictor of risk (hazard ratio of 1.16 per standard deviation, compared to 1.13 for LDL cholesterol and 1.14 for apolipoprotein B). That means for each standard deviation of increase in non-HDL cholesterol, there is a 16% higher chance of a major cardiovascular event (which includes myocardial infarctions, strokes, and  unstable angina).

I looked at my own LDL and non-HDL levels from my most recent blood tests and saw that I was near the average of the top quartile for both, making my hazard ratio (relative to the bottom quartile) 1.26 based on LDL and 1.42 based on non-HDL.  That means I have about a 42% higher chance of a stroke or heart attack than someone with the same age, gender, body mass index, … whose non-HDL levels were in the bottom quartile.

What I don’t know is whether more aggressive statin therapy is warranted in my case.  How does the increased risk of liver or muscle damage from higher doses of statins compare to decreased risk of heart attack or stroke?  Other than the inherited high cholesterol levels, the only risk factors I have are being male and over 55—I get a fair amount of aerobic exercise, don’t smoke, am not overweight, and don’t have high blood pressure.  According to online cardiac-risk factor calculators, my risk of a heart attack (or death from coronary heart disease) in the next 10 years is 8%–12% (depending on which calculator I use and what it considers).  Small changes in cholesterol (about what is achievable based on my 20 years of statin usage) can move me more solidly into the 8% risk category, but not really reduce the risk lower than that.  If the calculations were based on non-HDL cholesterol, they might assess my risk slightly higher.

2012 March 1

New FDA labels for statins

Filed under: Uncategorized — gasstationwithoutpumps @ 09:07
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In earlier posts, I talked about statin drugs (Simvastatin warning and Health Net screws me on their formulary).  This week, the FDA has made some changes in the labeling for all statins, based on the ongoing monitoring of the millions of patients taking the drugs:

There are 4 parts to the new changes:

  1. Liver Injury Called Rare It turns out that liver damage (the main side effect of statins that I’ve worried about) is rare enough that monitoring liver enzymes is no longer recommended.  The reasoning is that “no data exist to show that routine periodic monitoring of liver biochemistries is effective in identifying the very rare individual who may develop significant liver injury from ongoing statin therapy.”
  2. Reports of Memory Loss This one seems to be a scare message only—there have been anecdotal reports of cognitive loss in patients taking statins, but no controlled studies showing there is even a correlation, much less causation.  With millions of older people taking statins, one would expect reports of cognitive loss.  The question is whether the numbers are higher than among those not taking statins.  The data are not there to determine this, so the warning seems a bit misleading to me.
  3. The Risk of Diabetes There have been studies showing blood sugar increases in people taking statins, resulting in a 9% higher risk of diabetes.  I’m not at high risk of diabetes (I think), so multiplying that risk by 1.09 does not worry me, but I wonder whether doctors will be more likely to order tests for diabetes in their patients who take statins.
  4. The Potential for Muscle Damage The potential for rhabdomyolysis has always been present with statins (about 0.44 cases per 10,000 person years of treatment doi:10.1136/bmj.a2286. PMID 18988647), but is greatly increased when certain other drugs are taken at the same time, because of inhibition of the  metabolic machinery is involved in breaking down the statin.  The FDA is tightening the warnings for lovastatin being prescribed with certain other drugs.  It is not clear to me whether the warnings are restricted to lovastatin because that was the most commonly prescribed statin, and so the rare events were seen most often with it, or because lovastatin is metabolized differently from the other statins, and so the risks are higher, or whether the warnings were already in place for the other statins.  The statins do behave somewhat differently in the body (hence the large differences in effect as a function of dosage), so any of these explanations is plausible.  The FDA explains the interactions:

    Lovastatin is a sensitive in vivo cytochrome P450 3A4 (CYP3A4) substrate. Strong CYP3A4 inhibitors are predicted to significantly increase lovastatin exposure. A literature review indicates that itraconazole, a strong CYP3A4 inhibitor, increases lovastatin exposure up to 20-fold and the drug interaction appears to result in rhabdomyolysis. The effect of itraconazole on lovastatin exposure can therefore be extrapolated to other strong CYP3A4 inhibitors, including ketoconazole, posaconazole, erythromycin, clarithromycin, telithromycin, human immunodeficiency virus (HIV) protease inhibitors, boceprevir, telaprevir, and nefazodone.

    Note that grapefruit juice is an inhibitor of CYP3A4, which is why statin users are recommended not to eat grapefruit or drink grapefruit juice. According to the Wikipedia article on CYP3A4, atorvastatin, lovastatin, simvastatin, and cerivastatin are all CYP3A4 substrates, but pravastatin and rosuvastatin are not. If this is accurate, then the FDA warnings should probably have been extended to atorvastatin, simvastatin, and cerivastatin as well. Of course, cerivastatin has already been withdrawn from the market because of much higher rates of rhabdomyolysis than the other statins.

I’m switching from rosuvastatin to a higher dose of atorvastatin this week, thanks to Health Net making the copayment for rosuvastatin so high.  The only change that the new FDA labeling should have for me is that I’m unlikely to be getting liver enzyme tests in future—though I’ll still have to get a blood test every 6 months to monitor the cholesterol levels.

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