A growing amount of evidence has supported an association between elevated triglyceride levels and cardiovascular disease. However, little information regarding co-morbidities, levels of other cholesterol types, or medication use among adults with severe hypertriglyceridemia (SHTG; (500 to 2,000 mg/dl) is available. We examined the data from 5,680 subjects, ≥20 years old, who had participated in the National Health and Nutrition Examination Survey from 2001 and 2006, to evaluate the epidemiology of adults with SHTG. Approximately 1.7% of the sample had SHTG, equating to roughly 3.4 million Americans. The participants with SHTG tended to be men (75.3%), non-Hispanic whites (70.1%), and aged 40 to 59 years (58.5%). More than 14% of those with SHTG reported having diabetes mellitus, and 31.3% reported having hypertension. Only 14% of the subjects with SHTG reported using statins, and 4.0% reported using fibrates. The factors significantly associated with having SHTG included high-density lipoprotein <40 mg/dl (odds ratio [OR) 11.45, 95% confidence interval [CI] 6.28 to 20.86), non–high-density lipoprotein 160 to 189 mg/dl (OR 9.74, 95% CI 1.68 to 56.40) or non–high-density lipoprotein ≥190 mg/dl (OR 24.99, 95% CI 3.90 to 160.31), diabetes mellitus (OR 3.04, 95% CI 1.45 to 6.37), and chronic renal disease (OR 7.32, 95% CI 1.45 to 36.94). In conclusion, SHTG is rare among adults in the United States and the use of pharmacologic intervention is low among those with SHTG.
Little information is published regarding the epidemiology of adults with severe hypertriglyceridemia (SHTG; 500 to 2,000 mg/dl). Descriptive data on this condition are of public health importance, given that elevated serum triglycerides (TG) are associated with an increased risk of coronary heart disease and pancreatitis. Using data obtained from the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2006, our objectives were to estimate the distribution of high TG levels in the United States adult population, assess the distribution of TG levels as they relate to the use of dyslipidemic agents, and evaluate the association between SHTG and personal characteristics and habits, levels of other cholesterol types, co-morbidities, and medication use.
Methods
The present study used data from the NHANES (2001 to 2006) surveys. Specific details about NHANES have been provided by the Centers for Disease Control (available at: http://www.cdc.gov/nchs/nhanes.htm ). In brief, NHANES is a program of studies designed to assess the health and nutritional status of adults and children in the United States. The survey is unique in that it combines interviews and physical examinations. The data obtained from NHANES are our best resource for estimating the prevalence of SHTG in the United States adult population. The NHANES participants were initially interviewed in their homes and then were asked to visit a mobile examination center, where they completed additional questionnaires and underwent a physical examination and fasting blood draw.
In the past, the NHANES surveys were conducted on a periodic basis, and the data were released as single, multiyear data sets. For example, NHANES III covered the 6 calendar years from 1988 to 1994 and has generally been analyzed as a single 6-year survey. Since 1999, NHANES has been planned and conducted as a continuous annual survey. For a variety of reasons, including disclosure issues, the continuous NHANES survey data have been released as public use data files in 2-year increments (e.g., NHANES 2001 to 2002, NHANES 2003 to 2004, NHANES 2005 to 2006). For the present study, NHANES 2001 to 2006 were combined to achieve an optimal sample size for the analyses.
All adults who participated in the NHANES 2001 to 2006 were included in our study, except for those aged <20 years, pregnant and lactating women, and anyone for whom morning, fasting TG levels had not been taken.
Approximately 50% of the NHANES participants provided a fasting blood sample during a morning examination. On collection, the blood samples were stored at −20°C until they were shipped to the Lipoprotein Analytical Laboratory at Johns Hopkins University (Bethesda, Maryland) for testing. At the laboratory, the TG levels were measured enzymatically through a series of reactions in which the TGs were hydrolyzed to produce glycerol. Using glycerol oxidase, the glycerol was oxidized and eventually converted into phenoazone. The absorbance was measured at 500 nm . Quality control procedures, including the testing of blind quality control samples, were followed and can be found in the laboratory files for each survey at the NHANES Web site (available at: http://www.cdc.gov/nchs/nhanes/nhanes_questionnaires.htm ).
The following risk factors were included in our analysis and categorized as yes or no unless otherwise specified: gender (male or female); age (20 to 39, 40 to 59, and ≥60 years); race (non-Hispanic white, Mexican/Hispanic, non-Hispanic black, and other); smoking status (never, current, former); alcohol consumption; body mass index (under/normal weight <25, overweight 25 to <30, and obese ≥30 kg/m 2 ); total cholesterol (<200, 200 to <240, and ≥240 mg/dl); high-density lipoprotein (HDL; ≥60, 40 to 59, and <40 mg/dl); non-HDL (<130, 130 to 159, 160 to 189, and ≥190 mg/dl); C-reactive protein quintiles (0.01 to 0.06, 0.07 to 0.14, 0.15 to 0.28, 0.29 to 0.56, and 0.57 to 25.40 mg/dl); diagnosed diabetes mellitus; and a history of myocardial infarction, heart failure, coronary heart disease, hypertension, stroke, angina, chronic renal disease, liver disease, and hypothyroidism. In addition, the use of TG-raising medications, including levothyroxine, estrogens, and β blockers, was assessed. Information on the status of each of these diseases, conditions, or use of medications was obtained by participant self-report, with the exception of several diseases (i.e., liver disease and chronic renal disease), for which the variables were combined to classify the participants as having or not having the disease. Liver disease was defined as a total bilirubin >2 mg/dl, alanine aminotransferase >100 U/L, or aspartate aminotransferase >100 U/L. Chronic renal disease was defined as albuminuria (urine albumin/urine creatinine 100≥30) and an abnormal glomerular filtration rate. Stage 1 was albuminuria with an estimated GFR >90 ml/min/1.73 m 2 ; stage 2, albuminuria with an estimated GFR of 60 to 89 ml/min/1.73 m 2 ; stage 3, a GFR of 30 to 59 ml/min/1.73 m 2 ; stage 4, a GFR of 15 to 29 ml/min/1.73 m 2 ; and stage 5, a GFR of <15 ml/min/1.73 m 2 . The use of the following dyslipidemic agents alone and combined was also evaluated: niacin by prescription only, over-the-counter niacin, if the study participant reported taking ≥250 mg/day, statin, fibric acids, bile acid sequestrants, ezetimibe, and omega-3 (Lovaza or omega-3 supplements at a dose of ≥250 mg/day). Lovaza was combined with omega-3 supplements in the NHANES 2005 to 2006 data. We used the 2002 National Cholesterol Education Program guidelines to categorize the TG levels as follows: normal, <150 mg/dl; borderline high, 150 to 200 mg/dl; high, 200 to <500 mg/dl; and severe, 500 to 2,000 mg/dl. For a subset of our evaluation, the TG levels were dichotomized as severe (500 to 2,000 mg/dl) or not severe (<500 mg/dl).
Descriptive statistics, including the mean values for continuous variables and percentages for categorical variables, were used to summarize the data. The 95% confidence interval (CI) was calculated around all percentages. Crude and adjusted multivariate logistic regression models were used to calculate the odds ratios (ORs) and 95% CIs for the association between the risk factors and having SHTG. The adjusted models included the following covariates: gender, age, ethnicity, total cholesterol, HDL, non-HDL, smoking, alcohol, C-reactive protein quintiles, physical activity, body mass index, diagnosed diabetes, myocardial infarction, heart failure, coronary heart disease, hypertension, stroke, angina, chronic renal disease, liver disease, hypothyroidism, levothyroxine, estrogens, and β blockers. Statistical analyses were conducted using Statistical Analysis Systems, version 9.1 (SAS Institute, Cary, North Carolina).
Results
Our sample included 5,680 adults ≥20 years old who had participated in NHANES 2001 to 2006 and who had had the fasting TG level measured as a component of the NHANES. The distribution of TG levels in the sample are listed in Table 1 . More than 67% of the participants had normal TG levels, 14.2% had borderline high TG levels, and 16.3% had high TG levels. The prevalence of SHTG (500 to 2,000 mg/dl) was 1.7%, equating to roughly 3.4 million Americans. Three participants had TG levels >2,000 mg/dl. Given the small number, these patients were excluded from our analysis.
| Triglyceride Level (mg/dl) | ATP-III Guidelines Classification | Sample Size (n = 5,680) | Population Estimate (n = 197,088,927) | Percentage of Population |
|---|---|---|---|---|
| <150 | Normal | 3,812 | 133,660,634 | 67.8% |
| 150–200 | Borderline high | 839 | 27,933,114 | 14.2% |
| 200–<500 | High | 939 | 32,056,089 | 16.3% |
| 500–2,000 | SHTG | 87 | 3,357,214 | 1.7% |
| >2,000 | SHTG | 3 | 81,877 | 0.0% |
| Total | — | 5,680 | 197,088,927 | 100.0% |
The distribution of risk factors across the TG levels is listed in Table 2 . The participants with SHTG tended to be men (75.3%), non-Hispanic whites (70.1%), and aged 40 to 59 years (58.5%). In addition, a large majority of those with SHTG reported participating in habits that might be risk factors for elevated TG levels, including a current or former smoker (70.1%), consuming alcohol (71.5%), and participating in <150 minutes/week of exercise (64.0%). The lipid profiles of the participants with SHTG were not unexpected. More than 70% of the participants with SHTG had HDL levels <40 mg/dl, 73.5% had non-HDL cholesterol levels ≥190 mg/dl, 66.7% had total cholesterol levels of ≥240 mg/dl. The mean TG level for the participants with SHTG was 784.5 mg/dl compared to 272.6 mg/dl for the participants with high TG levels, 172.1 mg/dl for the participants with borderline high TG levels, and 92.7 mg/dl for those with normal TG levels. More than 14% of the those with SHTG reported having diabetes, and 31.2% reported having hypertension.
| Descriptive Variable | Serum TG Level (mg/dl) | |||
|---|---|---|---|---|
| <150 (n = 3,812) [n = 133,660,634] | 150–<200 (n = 839) [n = 27,933,114] | 200–<500 (n = 939) [n = 32,056,089] | 500–2,000 (n = 87) [n = 3,357,214] | |
| Gender | ||||
| Male | 46.2% (45–48) | 51.1% (48–54) | 59.2% (55–63) | 75.3% (62–89) |
| Female | 53.8% (52–55) | 48.9% (46–52) | 40.8% (37–45) | 24.7% (11–38) |
| Race/ethnicity | ||||
| Hispanic | 10.9% (8.7–13) | 12.2% (7.5–17) | 11.8% (8.0–16) | 14.9% (6.6–23) |
| Non-Hispanic white | 70.8% (67–74) | 75.2% (69–81) | 77.6% (73–83) | 70.1% (60–81) |
| Non-Hispanic black | 13.3% (11–16) | 6.3% (4.1–8.6) | 5.6% (3.8–7.4) | 5.7% (2.3–9.0) |
| Other | 5.1% (4.0–6.1) | 6.2% (4.1–8.4) | 4.9% (2.6–7.2) | 9.3% (0.7–18) |
| Age (years) | ||||
| 20–39 | 42.3% (40–45) | 28.1% (24–32) | 29.8% (25–34) | 31.1% (19–44) |
| 40–59 | 37.8% (36–40) | 43.0% (39–47) | 41.9% (38–46) | 58.5% (46–71) |
| ≥60 | 19.9% (18–22) | 28.9% (26–32) | 28.3% (25–32) | 10.4% (4.0–17) |
| Currently insured | 80.7% (78–83) | 82.0% (79–85) | 83.1% (80–86) | 67.7% (53–82) |
| Body mass index (kg/m 2 ) | ||||
| Underweight (<18.50) | 2.1% (1.5–2.7) | 0.2% (0.0–0.4) | 0.2% (0.0–0.5) | — |
| Normal weight (>18.50–<25) | 38.7% (37–40) | 17.8% (15–21) | 14.7% (12–17) | 10.5% (0.2–21) |
| Overweight (25–<30) | 31.1% (29–33) | 40.9% (37–45) | 36.6% (33–40) | 46.1% (36–57) |
| Obese (≥30) | 26.2% (24–28) | 39.0% (35–43) | 46.4% (43–50) | 43.5% (33–54) |
| Smoking status | ||||
| Current | 24.6% (23–27) | 23.4% (20–27) | 27.5% (24–31) | 39.9% (25–55) |
| Former | 23.4% (21–26) | 28.9% (25–33) | 28.7% (25–32) | 30.2% (18–42) |
| Never | 51.9% (49–55) | 47.6% (42–53) | 43.8% (40–47) | 29.9% (18–42) |
| Alcohol consumption | 67.8% (65–71) | 65.7% (61–70) | 64.4% (59–69) | 71.5% (57–86) |
| Physical activity (minutes/week) | ||||
| <150 | 54.2% (52–57) | 59.3% (55–64) | 64.3% (60–69) | 64.0% (53–75) |
| ≥150 | 45.8% (43–48) | 40.7% (36–45) | 35.7% (31–40) | 36.0% (25–47) |
| Abdominal obesity (cm) | ||||
| >102 (men), >88 (women) | 42.5% (40–45) | 64.3% (61–68) | 66.1% (62–70) | 63.5% (49–78) |
| ≤102 (men), ≤88 (women) | 54.8% (53–57) | 32.7% (29–36) | 30.7% (27–35) | 31.4% (18–45) |
| Carbohydrate (% total intake) | ||||
| <60 | 86.4% (85–88) | 83.7% (79–88) | 87.2% (84–90) | 89.3% (81–97) |
| ≥60 | 13.6% (12–15) | 16.3% (12–21) | 12.8% (9.8–16) | 10.7% (2.6–19) |
| High-density lipoprotein (mg/dl) | ||||
| <40 | 9.2% (7.9–10) | 22.8% (19–27) | 39.4% (36–43) | 70.4% (57–84) |
| 40–<60 | 52.4% (50–54) | 60.4% (56–65) | 52.2% (48–56) | 28.7% (15–42) |
| ≥60 | 38.4% (36–41) | 16.8% (14–20) | 8.4% (5.4–11) | 0.9% (0.0–2.8) |
| Non-HDL cholesterol (mg/dl) | ||||
| <130 | 47.9% (46–50) | 20.8% (18–23) | 12.6% (10–15) | 2.7% (0.0–6.8) |
| 130–<160 | 30.2% (28–32) | 32.1% (28–36) | 24.8% (22–28) | 6.3% (0.7–12) |
| 160–<190 | 15.2% (14–17) | 28.3% (24–32) | 30.1% (27–34) | 17.6% (6.4–29) |
| ≥190 | 6.7% (5.5–7.9) | 18.9% (16–22) | 32.5% (29–36) | 73.5% (61–86) |
| Total cholesterol (mg/dl) | ||||
| <200 | 61.5% (59–64) | 43.6% (39–49) | 35.5% (33–38) | 11.0% (3.9–18) |
| 200–<240 | 28.7% (27–31) | 35.3% (31–40) | 37.3% (33–41) | 22.3% (12–33) |
| ≥240 | 9.8% (8.4–11) | 21.1% (18–24) | 27.2% (24–30) | 66.7% (55–79) |
| Mean triglycerides | 92.7% (91.3–94.0) | 172.1% (170.6–173.6) | 272.6% (266.2–279.0) | 784.5% (698.3–870.7) |
| LDL levels (mg/dl) | ||||
| <100 | 34.4% (32–37) | 26.1% (23–30) | 31.4% (28–35) | 64.0% (53–75) |
| 100–<130 | 34.5% (32–37) | 31.0% (27–35) | 30.8% (27–34) | 19.1% (8.9–29) |
| 130–<160 | 21.4% (20–23) | 26.8% (22–31) | 22.8% (20–26) | 1.6% (0.0–4.3) |
| 160–<190 | 7.4% (6.2–8.6) | 11.7% (8.8–15) | 9.6% (7.5–12) | 10.5% (2.0–19) |
| ≥190 | 2.2% (1.6–2.9) | 4.5% (2.5–6.5) | 5.4% (3.6–7.1) | 4.8% (0.0–10) |
| C-reactive protein quintiles (mg/dl) | ||||
| 1 (0.01–0.06) | 16.0% (14–18) | 5.3% (3.7–6.9) | 3.8% (2.0–5.6) | 7.0% (0.4–14) |
| 2 (>0.06–0.14) | 23.6% (21–26) | 17.7% (14–21) | 17.9% (15–21) | 14.3% (3.4–25) |
| 3 (>0.14–0.28) | 21.0% (19–23) | 21.2% (18–25) | 20.9% (18–24) | 29.8% (17–42) |
| 4 (>0.28–0.56) | 19.6% (18–21) | 28.0% (23–33) | 28.3% (25–31) | 28.7% (17–40) |
| 5 (>0.56–25.40) | 19.8% (18–21) | 27.7% (24–32) | 29.1% (26–32) | 20.3% (10–31) |
| Hemoglobin A1c (%) | ||||
| <7 | 97.3% (97–98) | 95.0% (93–97) | 92.2% (90–94) | 82.%5 (77–88) |
| 7–<8 | 1.5% (1.1–1.8) | 2.1% (0.8–3.4) | 3.4% (2.0–4.8) | 4.3% (0.0–8.9) |
| 8–<9.5 | 0.6% (0.3–0.9) | 1.4% (0.4–2.4) | 2.0% (0.8–3.2) | 0.6% (0.0–1.9) |
| ≥9.5 | 0.5% (0.2–0.8) | 1.4% (0.5–2.4) | 2.0% (1.0–3.0) | 11.8% (6.7–17) |
| Co-morbidities (n) | ||||
| 0 | 57.9% (56–60) | 45.5% (41–50) | 39.6% (35–45) | 41.4% (29–54) |
| 1 | 25.0% (23–27) | 27.2% (22–32) | 31.6% (28–35) | 32.5% (18–47) |
| 2 | 9.4% (8.3–11) | 14.6% (12–18) | 15.1% (13–18) | 13.6% (2.9–24) |
| ≥3 | 7.7% (6.6–8.7) | 12.7% (10–15) | 13.7% (11–16) | 12.5% (5.2–20) |
| Diabetes mellitus | 5.2% (4.6–5.9) | 10.0% (7.4–13) | 12.5% (9.3–16) | 14.6% (5.8–23) |
| Myocardial infarction | 2.8% (2.2–3.5) | 3.5% (2.1–4.9) | 6.1% (4.5–7.8) | 1.7% (0.0–4.0) |
| Heart failure | 1.9% (1.5–2.4) | 2.5% (1.2–3.9) | 3.0% (1.7–4.2) | 1.7% (0.0–4.0) |
| Coronary heart disease | 3.1% (2.5–3.7) | 4.2% (2.8–5.7) | 5.0% (3.4–6.6) | 5.3% (0.1–10) |
| Hypertension | 25.5% (24–27) | 35.7% (31–40) | 41.0% (37–46) | 31.2% (20–42) |
| Stroke | 2.4% (1.8–3.0) | 3.2% (1.8–4.6) | 3.9% (2.5–5.3) | 3.0% (0.0–6.5) |
| Angina pectoris | 2.3% (1.7–2.8) | 3.0% (1.7–4.3) | 4.7% (3.0–6.3) | 1.6% (0.0–4.8) |
| Liver disease | 1.1% (0.8–1.5) | 2.0% (0.6–3.5) | 1.7% (0.6–2.7) | 2.8% (0.0–8.5) |
| Hypothyroidism | 9.2% (8.0–10) | 10.9% (7.9–14) | 11.6% (8.9–14) | 10.2% (1.8–19) |
| Cancer | 5.6% (4.6–6.5) | 7.4% (5.0–9.7) | 5.8% (3.9–7.8) | 9.5% (0.0–19) |
| Chronic kidney disease | ||||
| Stage 1 | 2.8% (2.2–3.4) | 2.6% (1.4–3.7) | 3.6% (2.6–4.7) | 9.9% (0.5–19) |
| Stage 2 | 3.5% (2.8–4.2) | 4.8% (3.1–6.4) | 7.0% (4.7–9.2) | 6.6% (1.2–12) |
| Stage 3 | 6.7% (5.6–7.7) | 11.7% (9.0–14) | 9.5% (7.2–12) | 6.6% (0.4–13) |
| Stage 4 | 0.2% (0.1–0.4) | 0.4% (0.1–0.8) | 0.4% (0.0–0.7) | — |
| Stage 5 | 0.2% (0.0–0.3) | 0.1% (0.0–0.2) | 0.2% (0.0–0.4) | — |
| Cortical steroid therapy | 1.3% (0.8–1.7) | 1.9% (0.7–3.0) | 1.3% (0.5–2.1) | — |
| Estrogen use | 8.5% (7.4–9.6) | 8.6% (5.8–11) | 9.1% (6.7–12) | 1.9% (0.0–4.6) |
| β-Adrenergic blocker | 6.8% (5.8–7.8) | 13.8% (11–17) | 15.7% (13–19) | 12.7% (4.3–21) |
| Levothyroxine | 5.6% (4.6–6.6) | 7.1% (4.9–9.2) | 8.8% (6.4–11) | 5.4% (0.0–12) |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
