Volume 115, Issue 6 , Pages 441-447, 15 October 2003
A randomized controlled trial of a Chinese herbal remedy to increase energy, memory, sexual function, and quality of life in elderly adults in Beijing, China☆
Article Outline
Abstract
Background
Chinese herbal medicines are commonly used to improve general health and well-being despite limited scientific data to support their efficacy. We conducted a randomized, double-blind, placebo-controlled trial to determine whether an herbal remedy that is used widely in China was associated with changes in quality of life, energy, memory, sexual function, and qi (the Chinese concept of “vital energy” that is important in general health).
Methods
Residents (n = 237) of Beijing, China, who were aged ≥60 years and had self-reported decreased energy, memory, or sexual function, were randomly assigned to take four tablets of a Chinese herbal formula or of an identical placebo, three times a day for 30 days. Patients returned for one follow-up visit after 30 days for assessment of all outcomes. The main outcome measures were changes in quality of life at 30 days as measured by the 12-Item Short Form Health Survey (SF-12) Mental and Physical Component Summary scales.
Results
Use of Chinese herbs was associated with a small benefit in the Mental Component scale (difference of 1.9 points; 95% confidence interval [CI]: 0.1 to 3.6) and no benefit in the Physical Component scale (difference of –0.1 points; 95% CI: –1.7 to 1.5) as compared with placebo. A small improvement in the qi scale was no longer significant after adjusting for baseline differences in this score between groups. There was no improvement in physical performance, memory, or sexual function. The herbal product was well tolerated.
Conclusion
Short-term use of a mixture of Chinese herbs was associated with a small benefit in one measure of mental health that is of unclear clinical importance.
Sales of herbal medicines, including traditional Chinese herbs, have increased markedly in the United States in the past decade and are now estimated to be more than $4 billion annually 1, 2. Recent surveys have found that 12% to 71% of adults in the United States have used an herbal product to treat an illness or improve health 3, 4, 5, 6.
Although there are numerous published reports in Chinese-language journals regarding the efficacy of Chinese herbs, the studies rarely follow accepted standards for randomized controlled trials (7). In a review of Chinese-language studies of herbal treatments for respiratory tract infections (8), Liu et al concluded that there was insufficient information to determine whether these studies used adequate methods to assess efficacy. However, because traditional Chinese herbal medicines are classified as dietary supplements in the United States, evidence of efficacy before marketing is not required. Still, a small number of high-quality studies have shown that Chinese herbs may have beneficial effects as treatment for certain conditions, including irritable bowel syndrome and hepatitis C 9, 10.
Longevity Treasure (Enwei Pharmaceutical Company, Chengdu, China) is a proprietary extract composed of 10 Chinese herbs (Table 1). This herbal product is believed to increase longevity, quality of life, energy, memory, sexual function, and qi, the Chinese concept of “vital energy” that is important in general health. Because the product is used widely in China and has not been associated with serious side effects, we sought to determine whether regular use of this product would lead to improved health in elderly Chinese adults.
Table 1. Chinese Herbs in the Active Treatment
| Herb | Percentage |
|---|---|
| Herba Epimedii | 0025 >8% |
| Fructus Lycii Chinensis | 15% |
| Cordyceps Sinensis | 15% |
| Herba Cynomorii Songarici | 8% |
| Herba Cistanches | 8% |
| Rhizoma Polygonati | 10% |
| Radix Astragali | 10% |
| Radix Rehmanniae | 10% |
| Glutinosae Conquitae | 8% |
| Radix Morindae Officinalis | 8% |
Methods
Subjects
Chinese adults aged 60 years or older were recruited by study assistants at the Peking Union Medical College Hospital in Beijing, China. To be eligible, patients had to have reported one of the following problems during the past year: decreased energy all or most of the time, poor or decreased memory, or decreased sexual interest.
Because this herbal formula consists of herbs that are believed to increase yang (or “fire” and “energy”), which is associated with hypertension, agitation, insomnia, and other health problems, patients with characteristic findings of high yang were excluded. High yang was defined as the presence of one or more of the following: high fever, restlessness, irritability, constipation, flushed face and congested eyes, excessive thirst and preference for cold drinks, dark yellow urine, or a red tongue with a dry, thick, and yellow coating.
Participants were also excluded if they had a history of cancer, had lost more than 5 kg involuntarily in the past year, were unable to walk independently, were unable to understand the study instructions, had a blood pressure of >160/100 mm Hg, had taken this herbal formula during the past month, or had baseline laboratory values (electrolytes, blood urea nitrogen, creatinine, glucose, complete blood count, liver function, prothrombin time) that were outside of a range of predetermined clinically normal values.
Intervention
Eligible patients were randomly assigned to take either four tablets of the herbal formula or of an identical placebo, three times a day for 30 days. The placebo and active tablets were found by the California State Department of Health (Food and Drug Branch, Sacramento, California) to be free of notable levels of lead, arsenic, mercury, and pharmaceutical drugs (as assessed by gas chromatography). Assignment to treatment and placebo groups was according to a randomization list that was generated using the “ralloc” procedure in STATA, version 7 (Stata Corporation, College Station, Texas).
All investigators, outcome assessors, study assistants, and patients were blinded to the treatment assignment and allocation sequences during the course of the study. Prenumbered identical containers reflecting the randomization sequence were administered serially to patients. Adequacy of blinding was assessed by comparing the percentage of patients in each group who believed they were taking active medication at the end of the study.
Outcomes
All outcome measures were assessed at baseline and after 30 days of treatment at the follow-up visit. The primary outcome measures were changes in quality of life as measured by the Physical and Mental Component Summary scales of the 12-Item Short Form Health Survey (SF-12). The SF-12 is widely used in measuring health and quality of life and has been shown to have a high level of agreement with scores from the original 36-Item Short Form Health Survey (SF-36) (11). The SF-36 has been validated in several Chinese studies, whereas evaluation of the SF-12 is ongoing (11). Secondary outcome measures included assessments of physical performance, memory, sexual function, and qi.
Measurements
Physical performance was assessed using five previously validated tests 12, 13, 14, 15, 16 that had been modified slightly in consideration of the safety of the elderly subjects. Patients were asked to stand up from a chair of standard height to a full standing position and then sit down again as many times as possible in 20 seconds (compared with 30 seconds [12]). They were also asked to tap the front of their foot up and down as many times as possible in 20 seconds while sitting in a chair of standard height. This test measures anterior tibialis muscle fatigue using voluntary rather than electrically stimulated contractions (13). Grip strength was tested by asking patients to squeeze a grip strength meter as tightly as possible for a few seconds and to repeat the process six times. Participants were also asked to step up and down on a 16-cm high step as many times as possible in 30 seconds. Finally, participants were told to walk and “cover as much ground as possible at a pace you can maintain for 6 minutes” on a flat indoor surface.
Memory was assessed using previously validated tests of short-term word recall, long-term word recall, and picture recall 17, 18. Sexual function was assessed using modified items from previously published questionnaires 19, 20. The first two items asked patients to rate their sexual interest and ability in the past month on a 0- to 10-point scale, and the summary score was the sum of these two items. The third item asked about the frequency of sexual activity in the past month.
The qi scale is a 17-item instrument (14 items on an interviewer-administered questionnaire and three physical examination items) that was developed through an international collaboration of clinical investigators with expertise in scale development and traditional Chinese medicine. Questionnaire items address symptoms commonly included in a traditional Chinese medical interview, including breathing, energy level, appetite, heartburn, sweating, bowel patterns, pain, temperature sensations, sleep habits, and sexual ability. The physical examination items address tongue coating, tongue muscle quality, and pulse quality. The scale was developed for this study and has not been validated (Appendix). The 14 questionnaire items are scored on a scale of 0 to 4 points, and the physical examination items are scored on a scale of 0 to 3. The total qi score is the sum of each score, ranging from 0 (best) to 65 (worst).
Patients were asked to call the study center if they experienced any medical problems during the 30-day study period. At the end of the study, they were also asked about adverse events. Laboratory tests were drawn at baseline and follow-up visits and compared to see whether any changes suggested adverse events.
The study was designed to detect a 3-point change in either of the SF-12 scales. The standard deviation of the change in the Physical and Mental Component Summary scales is approximately 6 points in this group of patients. Using a two-tailed α of 0.05, the study sample size of 223 patients resulted in 95% power to detect a change of 3 points in either of the SF-12 scales.
The study protocol and procedures were reviewed and approved by institutional review boards at the University of California, San Francisco, and the Peking Union Medical College Hospital, which has previously received certification as an accepted institutional review board by the National Institutes of Health.
Statistical analysis
Baseline characteristics between groups were compared using the Student t test for continuous variables and the chi-squared test for dichotomous variables. The Student t test was also used to compare the change in outcome measures between groups. Because baseline differences could bias the comparison of the change in outcome measures, we used a general linear regression model to adjust for outcomes that showed a statistically significant difference in baseline measurements.
Physical function scores were presented as means (± SD). An overall physical function score was calculated by transforming each physical function test into a z score and adding the z scores into a summary measure. Frequency of adverse events and the proportion of patients who believed they were taking active medication were compared using the chi-squared test. P values <0.05 were considered significant. All analyses were performed using SAS, version 8.2 (SAS Institute, Inc., Cary, North Carolina).
Results
Two hundred and thirty-seven patients satisfied the inclusion criteria (Figure) and were randomly assigned to the Chinese herb (n = 118) or placebo group (n = 119). Baseline characteristics were similar between treatment groups (Table 2), except for the qi score, which was lower (better) in the placebo group (13.8 points vs. 15.8 points, P = 0.01). Four patients in the placebo group and 10 patients in the Chinese herb group did not return for the follow-up visit (Figure), leaving 115 patients (97%) in the placebo group and 108 (92%) in the Chinese herb group for analysis.
Figure.
Flowchart showing enrollment and follow-up of study participants.
Table 2. Baseline Characteristics of the Patients Taking Chinese Herbs or Placebo
| Characteristic | Placebo (n = 119) | Chinese Herbs (n = 118) | P Value |
|---|---|---|---|
| Mean ± SD or Number (%) | |||
| Age (years) | 65.6 ± 4.6 | 66.4 ± 4.6 | 0.23 |
| Female sex | 74 (62) | 76 (64) | 0.72 |
| Decreased energy | 25 (21) | 30 (25) | 0.42 |
| Decreased memory | 97 (82) | 102 (86) | 0.30 |
| Decreased sexual interest | 116 (98) | 111 (94) | 0.19 |
| SF-12 physical health score* | 49.9 ± 6.5 | 49.2 ± 6.6 | 0.46 |
| SF-12 mental health score* | 53.1 ± 6.6 | 52.3 ± 6.6 | 0.40 |
| Qi scale† | 13.8 ± 5.1 | 15.8 ± 6.2 | 0.01 |
| Memory score* | 21.3 ± 4.6 | 20.3 ± 4.3 | 0.08 |
| Physical performance* | 0.3 ± 3.4 | −0.3 ± 3.5 | 0.13 |
| Sexual function score* | 4.1 ± 4.1 | 3.2 ± 3.9 | 0.09 |
| Education (years) | 11.0 ± 4.8 | 10.6 ± 4.6 | 0.49 |
| Systolic blood pressure (mm Hg) | 140.7 ± 14.0 | 139.1 ± 14.8 | 0.38 |
| Diastolic blood pressure (mm Hg) | 81.9 ± 8.6 | 82.1 ± 9.0 | 0.85 |
* Higher values indicate improvement. |
† Lower values indicate improvement. |
There was a small improvement in the Mental Component Summary scale in the Chinese herb group (1.9-point greater improvement over placebo; 95% confidence interval [CI]: 0.1 to 3.6; Table 3). No improvement was seen in the Physical Component Summary scale. The Chinese herb group had a slightly better score on the qi scale (–1.3 points; 95% CI: –2.6 to –0.1). However, the improvement was no longer statistically significant (difference = –0.3; 95% CI: –1.3 to 0.7) after adjusting for baseline differences. There were no differences between groups in the overall scores for memory, physical performance, and sexual function (Table 3).
Table 3. Change in Measurements after 30 Days of Treatment
| Measurement* (Score Range) | Change in Placebo Group (n = 115) | Change in Chinese Herb Group (n = 108) | Difference (Active-Placebo) in Change in Outcome Measure | P Value |
|---|---|---|---|---|
| Mean ± SD | Difference (95% Confidence Interval) | |||
| Quality of life | ||||
| SF-12 physical (0–100 points) | 1.7 ± 6.0 | 1.6 ± 6.1 | −0.1 (−1.7 to 1.5) | 0.89 |
| SF-12 mental (0–100 points) | 2.5 ± 6.8 | 4.4 ± 6.6 | 1.9 (0.1 to 3.6) | 0.04 |
| Qi scale (0–65 points) | −2.1 ± 4.2 | −3.4 ± 5.3 | −1.3 (−2.6 to −0.1) | 0.04 |
| Memory | ||||
| Total score (0–39 points) | 4.2 ± 3.7 | 4.5 ± 3.6 | 0.3 (−0.6 to 1.3) | 0.51 |
| Physical performance† | ||||
| Total score (−16 to 8 points) | −0.1 ± 2.6 | −0.1 ± 1.9 | 0.1 (−0.5 to 0.7) | 0.80 |
| Chair stands (0–19 stands) | 1.6 ± 2.2 | 1.7 ± 1.8 | 0.1 (−0.4 to 0.6) | 0.73 |
| Foot taps (0–58 taps) | 7.0 ± 6.0 | 6.6 ± 5.4 | −0.4 (−1.9 to 1.1) | 0.60 |
| Grip (0–46.3 pounds) | 0.5 ± 2.5 | 0.3 ± 2.6 | −0.2 (−0.9 to 0.5) | 0.56 |
| Step test (0–25 steps) | 1.9 ± 2.6 | 1.9 ± 2.2 | 0.0 (−0.7 to 0.6) | 0.92 |
| Distance walked (0–714 m) | 9.4 ± 54.1 | 16.0 ± 32.4 | 6.6 (−5.2 to 18.5) | 0.27 |
| Sexual function | ||||
| Total score (0–20 points) | −1.0 ± 3.0 | −0.4 ± 1.9 | 0.6 (0.0 to 1.3) | 0.06 |
| Frequency (0–6 episodes) | −0.2 ± 0.7 | −0.1 ± 0.6 | 0.1 (−0.1 to 0.3) | 0.20 |
* For all tests, a higher value represents improvement, except for the qi scale, where a lower value indicates improved qi. |
† Individual physical performance scores were calculated as follows: chair stands = number of stands in 20 seconds; foot taps = number of taps in 20 seconds; grip strength = average grip strength of six trials; step test = number of times up and down a standard step in 30 seconds; distance walked = number of meters walked on a flat surface in 6 minutes; total score = sum of the z score for all five tests. |
A total of 54 adverse events were reported by 47 patients: 31 in the Chinese herb group and 23 in the placebo group (Table 4). The only adverse event that appeared to be more common in the Chinese herb group was dry mouth (15 events vs. 7 events, P = 0.07). There was no significant difference in the total number of adverse events between treatment groups. None of the study patients experienced a serious adverse event during the study period.
Table 4. Adverse Events in the Treatment and Placebo Groups*
| Adverse Event | Placebo (n = 119) | Chinese Herbs (n = 118) | P Value |
|---|---|---|---|
| Number (%) | |||
| Headache | 0 | 1 (0.9) | 0.31 |
| Upper respiratory tract infection | 1 (0.8) | 1 (0.9) | 1.00 |
| Oral ulcer | 0 | 2 (1.7) | 0.15 |
| Dry mouth | 7 (5.9) | 15 (12.7) | 0.07 |
| Chest pain | 1 (0.8) | 0 | 0.32 |
| Nausea | 1 (0.8) | 1 (0.9) | 1.00 |
| Diarrhea | 4 (3.4) | 2 (1.7) | 0.41 |
| Constipation | 4 (3.4) | 2 (1.7) | 0.41 |
| Flatulence | 3 (2.5) | 4 (3.4) | 0.69 |
| Cough | 1 (0.8) | 0 | 0.32 |
| Insomnia | 0 | 2 (1.7) | 0.15 |
| Other | 1 (0.8) | 1 (0.9) | 1.00 |
| Total | 23 | 31 | 0.24 |
* Adverse event information was obtained on all patients including those who had dropped out before follow-up (4 placebo, 10 Chinese herb). |
Analysis of the laboratory data showed only one statistically significant change (Table 5); white blood cell count decreased 0.4 points more (95% CI: –0.6 to –0.1) in the Chinese herb group than in the placebo group.
Table 5. Change in Laboratory Values after 1 Month of Treatment
| Laboratory Test | Normal Range | Change in Chinese Herb Group Compared with Placebo Group (95% Confidence Interval) | P Value |
|---|---|---|---|
| Sodium (mmol/L) | 135–145 | 0.2 (−0.4 to 0.8) | 0.53 |
| Potassium (mmol/L) | 3.5–5.5 | 0.0 (−0.1 to 0.1) | 0.89 |
| Chloride (mmol/L) | 96–111 | 0.5 (−0.3 to 1.2) | 0.24 |
| Bicarbonate (mEq/L) | 20–34 | −0.1 (−0.8 to 0.5) | 0.67 |
| Blood urea nitrogen (mg/dL) | 3–20 | 0.5 (−0.3 to 1.4) | 0.21 |
| Creatinine (mg/dL) | 0.6–1.5 | 0.0 (0.0 to 0.0) | 0.83 |
| Glucose (mg/dL) | 65–109 | −1.6 (−4.4 to 1.2) | 0.26 |
| White blood cell count (103/μL) | 4.8–10.8 | −0.4 (−0.6 to −0.1) | 0.01 |
| Hematocrit (%) | 38–52 | −0.3 (−1.2 to 0.6) | 0.48 |
| Platelets (103/μL) | 140–400 | 1.3 (−7.2 to 9.9) | 0.76 |
| International normalized ratio | — | 0 | 0.47 |
| Low-density lipoprotein cholesterol (mg/dL) | <130 | 0.4 (−0.1 to 9.8) | 0.94 |
| Aspartate transaminase (U/L) | 5–35 | 0.6 (−1.2 to 2.4) | 0.50 |
| Alanine transaminase (U/L) | 7–56 | 1.4 (−0.9 to 3.7) | 0.23 |
| Alkaline phosphatase (U/L) | 40–125 | 0.6 (−1.7 to 3.0) | 0.61 |
| Total bilirubin (mg/dL) | 0.1–1.2 | 0.0 (0.0 to 0.1) | 0.26 |
At the end of the study, a higher percentage of patients in the Chinese herb group believed they had taken active pills compared with in the placebo group (66% [71/108] vs. 45% [52/115], P = 0.002).
Discussion
Chinese herbs are widely prescribed, marketed, and used to improve general health despite limited information about their safety and efficacy. In this study, we found that daily use of a standardized extract of 10 Chinese herbs for 1 month led to a small benefit in only one of the two primary outcome measures, the SF-12 Mental Component Summary scale.
We attempted to measure changes in both a standard “Western” measure of quality of life (the SF-12 scale) and an “Eastern” measure (the qi scale). The improvement observed in the qi scale was no longer statistically significant after adjusting for baseline differences in this scale between groups, suggesting that the improvement may have been due to the Chinese herb group having worse initial qi scores and therefore a greater opportunity to improve, rather than to any actual benefit from the Chinese herbs. The scale, however, may not be an adequate measure of this complex Chinese concept of overall health. No improvements were seen in the secondary outcome measures of physical performance, memory, and sexual function.
We cannot determine whether the small benefit observed in the Mental Component Summary scale represents a true beneficial effect from the Chinese herbs or merely a chance finding in a study that has several measurements of outcome. The small magnitude of benefit, the borderline statistical significance of the benefit (P = 0.04), and the lack of statistically significant benefits in the other outcomes suggest that the mental health benefit may be a chance finding unrelated to the use of this mixture of herbs.
The magnitude of the observed benefit in the Mental Component Summary scale was small (1.9 points). In comparison, patients recovering from major depression had a mean improvement of 10 points on that scale (11). We do not know whether the small change we observed is likely to lead to a notable improvement in quality of life. Many experts in traditional Chinese medicine believe that Chinese herbal treatments may take 3 months or more to achieve the maximum effect. Thus, a longer treatment period might lead to more substantial improvements in mental health and other outcome measures.
A higher percentage of patients in the Chinese herb group believed they were taking active medication rather than placebo at the end of the study. It is not possible to determine whether this indicates that blinding was inadequate, or that patients in the active group perceived some effect and therefore concluded they were taking active medication. Analysis of adverse event data suggests that short-term use of this product is safe. The small decrease in the white blood cell count may be a chance finding and does not likely represent a clinically important change, but this test should be monitored if long-term studies are undertaken.
In conclusion, our results suggest that short-term use of a mixture of Chinese herbs (Longevity Treasure) may lead to a small improvement in mental health. Because this improvement was the only observed benefit in our study, and this benefit was small, further studies are needed to confirm these findings and determine whether longer treatment periods might lead to clinically important changes in other measures of quality of life.
Acknowledgements
We would like to thank the study staff (Muxian Chu, Su Zeng, Yanzhen Wei, Liangyu Liu, Xouhua Wang, Shuzhen Cui, Jing Zhou) at Peking Union Medical College Hospital, Beijing, China, for their dedication, outstanding work, and helpful suggestions regarding the optimal conduct of this trial.
Appendix. Qi scale
*.
| Questionnaire Items* | ||||
| 1. How often are you short of breath? | ||||
| Never | After moderate activity | After a little activity | Often | Always |
| 2. How often do you experience fatigue? | ||||
| Never | Sometimes, but still can do some activities | Can do daily activities with difficulty | Cannot do any daily activity | Stay in bed all day |
| 3. Have you ever had no desire to talk? | ||||
| Never | Not very talkative | Don't like to talk; answer questions with few words | Don't like to talk; answer questions with low voice | Don't want to talk; don't answer any question |
| 4. Has your appetite decreased? | ||||
| No | Minimal amount | Decreased by 1/4 | Decreased by 1/2 | Decreased by ≥3/4 |
| 5. Have you ever had heartburn after meals? | ||||
| Never | A little bit, disappears in 1/2 h, no medicine needed, no effect on daily activity | Improves in 1/2 to 1 h, requires medicine, affects daily activity | Lasts ∼2 h, no improvement with medicine | Lasts all day |
| 6. Do you sweat without activity or exertion? | ||||
| Never | A little wet without moving, wet with some movement | Wet without moving, wet with some movement | Always sweat moderately | Always sweat heavily |
| 7. Has your stool ever been soft? | ||||
| Never | Soft and no shape, once or twice a day | Soft and no shape, ≥3 times a day | Watery, 1–3 times a day | Watery, >3 times a day |
| 8. How often do you feel dizzy with ringing in the ear? | ||||
| Never | Occasionally | After activities or body movement | Often; improves after rest | Always, no improvement, even after rest |
| 9. How often you feel anxiety? | ||||
| Never | Occasionally | Sometimes | Often; decrease after rest | Always, no improvement, even after rest |
| 10. How often do you have insomnia? | ||||
| Never | Hard to fall asleep, don't sleep deeply, or wake up early, activities not affected | Sleep <6 h, perform daily activity with slight difficulty | Sleep <4 h, hard to perform daily activity | Unable to sleep whole night, cannot perform daily activity |
| 11. How often do you have pain in the lower back to knee? | ||||
| Never | Occasionally | After some activities | Often, decrease after rest | Always, no improvement |
| 12. Are you afraid of cold or are your hands and feet always cold? | ||||
| Never | Hands and feet always cold in cold weather | Hands and feet cold all the time | Hands and feet always cold and need to keep them warm | The whole body is always cold and need to keep it warm |
| 13. How often do you feel lack of energy? | ||||
| Never | Low energy, improve after rest | Low energy, don't improve after rest | No energy | No energy, slow reaction time |
| 14. Is your sexual ability decreased? | ||||
| Never | Decreased sexual desire, still have sexual ability | Occasion sexual desire, still have sexual ability | Occasion sexual desire, impotent | No sexual desire, impotent |
| Physical Examination Items† | ||||
| 1. Tongue Coating: | ||||
| Thin white | Slightly thick white | Thick white | No coating | |
| 2. Tongue Muscle: | ||||
| Light red | Light, no red | Light fat | Light fat with crack | |
| 3. Pulse: | ||||
| Normal | Slightly weak | Weak | Weak and not continuous | |
* Scoring is from left (0 points) to right (4 points). |
† Scoring is from left (0 points) to right (3 points). |
References
- Herbal and botanical U.S. consumer sales 1999. Nutrition Business Journal. 2000:1-3
- Brody JE. Americans gamble on herbs as medicines. New York Times. February 9, 1999;sect D1
- Self-treatment with herbal and other plant-derived remedies—rural Mississippi, 1993. MMWR Morb Mortal Wkly Rep. 1995;44:204-207
- Trends in alternative medicine use in the United States, 1990–1997 (results of a follow-up national survey). JAMA. 1998;280:1569–1575
- . Prevalence of use of herbal products by adults in the Minneapolis/St Paul, Minn, metropolitan area. Mayo Clin Proc. 2001;76:688–694
- The Landmark Report on Public Perceptions of Alternative Care. Sacramento, California: Landmark Healthcare; 1998
- . The CONSORT statement (revised recommendations for improving the quality of reports of parallel-group randomized trials). JAMA. 2001;285:1987–1991
- . Chinese herbal medicine in the treatment of acute respiratory tract infections (review of randomized and controlled clinical trials). Clin Infect Dis. 1999;28:235–236
- Preliminary report of a randomized, double-blind placebo-controlled trial of a Chinese herbal medicine preparation CH-100 in the treatment of chronic hepatitis C. J Gastroenterol Hepatol. 1998;13:244–247
- Treatment of irritable bowel syndrome with Chinese herbal medicine (a randomized controlled trial). JAMA. 1998;280:1585–1589
- . SF-12 (How to Score the SF-12 Physical and Mental Health Summary Scales). 3rd ed. Lincoln, Rhode Island: Quality Metric Incorporated; 1998;
- . A 30-s chair-stand test as a measure of lower body strength in community-residing older adults. Re Q Exerc Sport. 1999;70:113–119
- Development and reversal of fatigue in human tibialis anterior. Muscle Nerve. 1993;16:1239–1245
- . Dynamometer measurements of hand-grip strength predict multiple outcomes. Percept Mot Skill. 2001;93:323–328
- . A self-paced step test to predict aerobic fitness in older adults in the primary care clinic. J Am Geriatr Soc. 2001;49:632–638
- Prediction of mortality and morbidity with a 6-minute walk test in patients with left ventricular dysfunction. SOLVD Investigators. JAMA. 1993;270:1702–1707
- . The construction of “the clinical memory test”. ACTA Psychol Sinic. 1986;1:100–108
- . A study of memory disorder in patients with cerebral infarction [in Chinese]. Zhonghua Shen Jing Jing Shen Ke Za Zhi. 1988;21:212–215 254–255
- Assessment of sexual function in depressed, impotent, and healthy men (factor analysis of a brief sexual function questionnaire for men). Psychiatry Res. 1988;24:231–250
- . The use of validated questionnaires to assess female sexual dysfunction. World J Urol. 2002;20:89–92
☆ This work was supported by grant KO8 AT01338-01 to Dr. Bent from the National Center for Complementary and Alternative Medicine, Bethesda, Maryland, and by a grant from Enwei Pharmaceutical Company, Chengdu, China. Enwei Pharmaceutical Company had no role in the design, analysis, or reporting of the results of this investigation.
PII: S0002-9343(03)00421-2
doi:10.1016/S0002-9343(03)00421-2
© 2003 Excerpta Medica Inc. All rights reserved.
Volume 115, Issue 6 , Pages 441-447, 15 October 2003
