Of the 44,287 active-duty cohort members in this study, 29% (n = 12,717) reported using at least one practitioner-assisted CAM therapy, 27% (n = 11,996) reported using at least one self-administered CAM therapy and 61% (n = 26,982) reported not using any CAM therapy within the last 12 months. The frequency of the 12 CAM therapies reported for both men and women were massage therapy (24.7%), relaxation therapy (21.1%), spiritual healing (9.1%), chiropractic care (8.1%), herbal therapy (7.1%), high-dose megavitamin therapy (3.2%), folk remedies (2.3%), energy healing (1.4%), acupuncture (1.3%), homeopathic remedies, (1.3%), biofeedback (0.7%), and hypnosis (0.5%). Women reported the use of spiritual healing (13.5%) and herbal therapy (11.2%) at about twice the rate of men (7.3% and 5.5%, respectively). The other 10 CAM therapies showed similar use between men and women (data not shown).
Demographic and military characteristics of the study population by CAM use are shown in Table . Women reported a higher proportion of both practitioner-assisted (38.4%) and self-administered CAM use (35.4%) compared with men (24.8% and 23.7%, respectively). Reporting practitioner-assisted CAM therapies was highest among the following: women, younger individuals, those with a high school diploma or less, those who never married or were divorced, those serving in the Marine Corps, health care workers, healthy-weight individuals, current smokers, those reporting alcohol-related problems, and those reporting having one or more health conditions or symptoms. Individuals reporting one or more health conditions were 15% more likely to report CAM use and 19% more likely to report CAM use if reporting one or more health symptoms compared to non-CAM users (see Additional file 1
for list of health symptoms and conditions). Results for self-administered CAM use were very similar to practitioner-assisted CAM, with only a few exceptions. Those reporting self-administered CAM use showed a higher percentage of use among enlisted, Navy and Coast Guard, and under-weight individuals. Both the Mental and Physical Component Summary scores derived from the SF-36V were slightly lower in CAM users compared to nonusers.
Demographic and military characteristics of 2004-2006 active-duty Millennium Cohort participants by complementary and alternative medicine use (N = 44287)
A total of 1,449 first hospitalizations occurred among this active-duty cohort within 12 months of completing the Millennium Cohort questionnaire. First hospitalization rates and adjusted odds ratios for demographic and military characteristics are displayed in Table . Only two characteristics were statistically associated with a hospitalization independent of CAM use: being female 1.93 (95% CI: 1.69-2.19) or being a current smoker 1.20 (95% CI: 1.05-1.36). Birth year, education level and service branch were statistically significant for a lower probability of having a hospitalization during the study period when compared with their respective reference groups.
First hospitalization rates and adjusted odds ratios for active-duty military personnel over a 1-year period enrolled in the Millennium Cohort Study 2004-2006 (N = 42896)*
The unadjusted first hospitalization rate for non-CAM users was 30.5 per 1,000 and 39.0 per 1,000 for CAM users. When considering self-administered and practitioner-assisted types of CAM alone and in combination, the rate for practitioner-assisted only was 38.4 per 1,000, self-administered only was 32.9 per 1,000, and both was 43.3 per 1,000 (Table ). Unadjusted and adjusted odds ratios for first hospitalizations are also shown in Table . Unadjusted odds of hospitalization among CAM users was 1.29 (95% CI: 1.16-1.43). After adjusting for covariates and differences in comorbidities (propensity scores) the adjusted odds of hospitalization for CAM users compared to nonusers diminished in magnitude and became statistically nonsignificant 1.04 (95% CI: 0.93-1.17). We observed a higher probability of being hospitalized among those who reported using energy healing, chiropractic, relaxation, or massage therapies. Those using energy healing were hospitalized primarily for mental disorders, and those using chiropractic, relaxation, or massage therapy were primarily seen for diseases of the musculoskeletal system (data not shown).
First hospitalization rates by CAM use, unadjusted and adjusted odds ratios for active-duty military personnel
Active-duty Millennium Cohort participants were also evaluated for amount of time spent utilizing inpatient or outpatient care by CAM use. The mean number of days spent in outpatient health care for CAM users was 7.0 days and 5.9 days for non-CAM users (p < 0.001), while the mean number of days spent in inpatient care was 3.2 days and 3.1 days, respectively (p = 0.85). Thirty-nine percent of persons reporting CAM use accounted for 45.1% of outpatient care and 44.8% of inpatient care.
Separate multivariable logistic regression analyses across 15 broad ICD-9-CM categories, including pregnancy and childbirth, were conducted modeling inpatient or outpatient visits by CAM use. Figure illustrates each of the odds ratios for inpatient hospitalization discharge diagnoses models (excluding diseases of the blood due to sparse cases). Only hospitalization for nervous system diseases was statistically higher among those reporting CAM use compared to non-CAM users 2.72 (95% CI: 1.28-6.70). We found the majority of ICD-9-CM codes for nervous systems hospitalizations (n = 31) were for unspecified causes of encephalitis (ICD-9-CM 323.9), migraine unspecified (ICD-9-CM 346.9), and optic neuritis (ICD-9-CM 377.3). Mental disorders showed a slightly reduced odds ratio for hospitalization in CAM users 0.68 (95% CI: 0.47-0.97).
Adjusted odds ratios and 95% confidence intervals for odds of a hospitalization visit for illnesses by CAM use versus non-CAM use, adjusted for sex, age, education, marital status, race/ethnicity, pay grade, branch of service, and occupation.
When outpatient visits were examined (Figure ), CAM users were more likely to have had an outpatient visit for musculoskeletal system diseases 1.24 (95% CI: 1.21-1.26), mental disorders 1.22 (95% CI: 1.19-1.25), and injury and poisoning 1.08 (95% CI: 1.04-1.11). CAM users were less likely to been seen for the following: skin and subcutaneous diseases, circulatory diseases, pregnancy complications, digestive system diseases, nervous system diseases, neoplasms, and endocrine, nutritional, and metabolic disorders.
Adjusted odds ratios and 95% confidence intervals for odds of an outpatient visit for illnesses by CAM use versus non-CAM use, adjusted for sex, age, education, marital status, race/ethnicity, pay grade, branch of service, and occupation.