Factors associated with free adult preventive health care utilization among physically disabled people in Taiwan: nationwide population-based study

Background Few previous studies have specifically addressed the health care utilization situation of the physically disabled. This study aimed to investigate the utilization of free adult preventive health care for physically disabled people and its’ affecting factors. Methods The data was obtained from three nationwide databases from 2006 to 2008. This study comprised 329,264 physically disabled people in Taiwan above the age of 40 who had eligible health checks during 2008. We employed descriptive statistics to analyze the use and rate of free preventive health care use by physically disabled adults. Logistic regression analysis was used to explore the factors that affect physically disabled adults’ use of free adult preventive health care. Results 16.37% of the physically disabled adults used free adult preventive health care. Women (17.66%), married (17.16%), a junior high education level (17.89%), and mildly disabled adults (18.77%) had the highest use rate among various participant subgroups. The variables that significantly influenced the use of free adult preventive health care by the physically disabled included gender, age, education, marital status, urbanization of the residence areas, monthly payroll, aboriginal status, catastrophic illnesses status, relevant chronic diseases, and severity of disability. Conclusions Physically disabled using preventive health care tend to be low. Governments should use the media to reinforce propagation and education of these services to specific, low-utilization groups, and encourage doctors to actively provide preventive health care to communities. Electronic supplementary material The online version of this article (doi:10.1186/s12913-014-0610-5) contains supplementary material, which is available to authorized users.


Background
Because nerve damage from an injury in physically disabled people causes chronic pain [1,2], depression [3], and other complications, these patients lack the motivation to participate in various activities. Physically disabled people often have a sedentary lifestyle, leading to become overweight and obese [4][5][6]. Being overweight and obese cause changes in the modes of carbohydrate metabolism, increasing the prevalence of diabetes, hyperlipidemia, hypertension, and cardiovascular disease [7,8]. A 2002 study showed that people with disabilities in their lower extremities are 2.5 times the overweight and obesity ratio of average persons, and 40% of people with chronic spinal cord injuries are overweight or obese [9].
Nosek et al. [10] found that physically disabled women had 4 times the likelihood of suffering from diabetes, and 2 times the likelihood of suffering from hypertension than do average women. Studies have shown that those with spinal cord injuries have a higher prevalence of diabetes and coronary heart disease [11][12][13]. Poliomyelitis patients have a higher hyperlipidemia occurrence than the average person, and typically have two or more coronary artery disease risk factors [14]. Until the end of 2011, Taiwan's physically disabled population (386,217 people) accounted for 1.66% of the total population, and constituted the group with the most people (35.09%) [15,16] with mentally or physically disabilities (handicapped).
The disabled population has increased annually, consuming the government's health care and long-term care resources and producing a significant financial burden and challenge for society [17][18][19][20]. Maciosek et al. [21] believed that if the government expanded the promotion of free preventive health care utilization for all population, it would save US $3.7 billion annually in medical care expenditures. Increasing the utilization of free preventive health care can delay disease progression, reduce the severity of the disease, and effectively reduce medical expenses derived from complications [22][23][24][25]. Eliminating the inequities of disabled persons in health and medical care is the goal of the US Healthy People for 2020 [26].
Besides the cancer screening, Taiwan Health Promotion Administration provides at least six free preventive health care programs, including mammography, pap smear test, prenatal examination for pregnant women, children preventive health services, adult preventive health services, and children dental examination with fluoride varnish. The adult free preventive health care includes physical examinations, health education, and blood and urine tests. Adults aged 40 and above are legible this free service, but different age groups have varying frequency limits.
Because of the low mobility of physically disabled people, their medical care time is lengthened. Difficulties in receiving free preventive health care among the disabled people would lead to delay in receiving appropriate medical care. Previous studies showed gender, marital status [16], educational level, age, income, health status, severity of disability, and urbanization level would influence the utilization of preventive health services for the disabled people [27]. Much of the literature related to the disabled people focused on the secondary conditions of the disability, leaving a scarcity of research on the preventive health care needs of this disabled population. Few previous studies have specifically addressed the health care utilization situation of the physically disabled. This study used physically disabled people as participants to explore their free adult preventive health care utilization and its related factors, and to serve as a reference for adjusting preventive health policies for disadvantaged groups.

Data source and participants
The premise for the use of free adult preventive health care includes (1) people suffering from poliomyelitis and older than 35 years (use once a year), (2)  This study comprised 329,264 physically disabled people in Taiwan above the age of 40 who had eligible health checks during 2008. Among these, 153,117 were mildly disabled, 128,201 were moderately disabled, 44,097 were severely disabled, and 3,849 were extremely severely disabled. Among the 35 to 39 year-old disabled adults, since there was no way to distinguish who were poliomyelitis persons in the Disabled People Registry File and we could not analyze the utilization rate and likelihood of using preventive health care, this group was excluded when the analyses were conducted.
In the present study, demographic characteristics and severity of disability were obtained from the Disabled People Registry File (2008). Socioeconomic status, health status, and the environmental factor were merged from the National Health Insurance Research Database, which is publicly available. The information of using the free adult preventive health care among the physically disabled people was identified from the free preventive health care file (2006 to 2008).
After we applied and were approved to use these three databases, the personal identifications including ID number and name were used to exactly match all people's data or information in these three databases in the Statistics Center of the Ministry of Health and Welfare, Taiwan. All personal information could be completely linked among these three national databases. All individual's identification information has been deleted and personal privacy was protected in using these data. This study was approved by the research ethics committee of China Medical University and Hospital (IRB No. CMU-REC-101-012).

Variables description
The variables in this study were (1) demographic characteristics (i.e., gender, age, marital status, education, aboriginal status); (2) socioeconomic status (i.e., monthly insured payroll); (3) health status (i.e., catastrophic illness/injury, type of chronic illnesses including 15 comprehensive categories of chronic diseases such as cancer, endocrine and metabolic disease, mental illness, disease of nervous system, disease of circulatory system, disease of respiratory system, disease of digestive system, disease of urinary system, disease of skeletal and muscular system and connective tissue, disease of eyes and auxiliary organs, infectious disease, congenital malformation, skin and subcutaneous tissue disorders, disease of blood and bloodforming organs, and disease of ear and mastoid process), severity of disability (i.e., very severe, severe, moderate, and mild); and (4) environmental factors (i.e., urbanization level of residence area, URA; eight levels: Level 1 being the highest urbanized areas, and Level 8 being the lowest). The dependent variable that whether the physically disabled persons used the adult preventive health care was identified in the year 2008 for those aged 65 or older(once per year) and identified in the period of 2006-2008 for those aged between 40 and 64 (once every three years). The other relevant independent variables, including demographic, socioeconomic, health status, severity of disability, and environmental factors were obtained in the year 2008 from three national databases. The chronic disease groups used in this study were based on "the Range of Chronic Diseases" in the National Health Insurance Research Database. The chronic diseases listed in the Range of Chronic Diseases were defined by the Bureau of National Health Insurance in Taiwan, which consisted of 16 categories of chronic diseases. (Additional file 1). Since the "others" category had very few patients in the disabled people, this study excluded the "others" category in our analysis.

Statistical analysis
This study used descriptive statistics analysis, chi-squared test, and multiple logistic regression analysis to explain the relationship between the variables. The first step used descriptive statistics to analyze the physically disabled people's free adult preventive health care utilization quantity and ratio, focusing on their demographic characteristics, socioeconomic status, health status, environmental factors, and other variables. The second step used the chi-square test to compare the difference in physically disabled people's use of free preventive health care. Since all variables had a p value <0.05 in the chi-squared test in Table 1, we placed all variables into the logistic regression analysis to explore the factors that affected the use of free adult preventive health care among the physically disabled people.
Under the criteria for assessing model fit, the loglikelihood statistics for the fitted model indicated the model fitted well. This study used statistical software package SAS version 9.3 as an analysis tool. Statistics less than P <0.05 were significant.

Results
Physically disabled people's basic information Table 1 showed that there were 329,264 physically disabled people during 2006 to 2008. Over half of these were male (58.2%; n = 191,566). In the age category, most participants were older than or equivalent to 70 years of age (34.2%; n = 112,521), followed by participants between 45 and 49 (14.4%, n = 47,257). More than half of the participants were married (58.5%; n = 192,456). Participants with education levels less than or equivalent to elementary school accounted for the majority (51.1%; n = 168,180), followed by junior high level (14.9%; n = 49,103). Regarding monthly insured payroll, the insured dependent population accounted for the majority (i.e., children and spouses; 34.0%; n = 111,998). There were few people of aboriginal status, only accounting for 2.2% (n = 7,105). Mildly disabled (46.5%; n = 153,117) was the largest group in the physical disability severity level category.
Physically disabled people's free preventive health care utilization In this study, 16.4% (n = 53,913) of the physically disabled utilized free adult preventive health care (Table 1). Men and women's utilization rates were 15.5% and 17.7% (P <0.05), respectively. The men's utilization rate was slightly lower than the women's. Regarding age distribution, the 50 to 64 year-old group had the higher physically disabled utilization rate, more than 20%. The 60 to 64 year-old group had the greatest utilization (25.6%). Married people had a higher utilization rate (17.2%) than did the others (15.2% -15.7%, P <0.05). For education, junior high and senior (vocational) high school had greater utilization rates: 17.9% and 17.1%, respectively. Those with URA Level 8 had the greatest utilization rate (19.1%), and Level 1 had the smallest (10.9%). For income, those with a monthly insured payroll of NT $30,300 to 36,300 (22.3%) had the highest rate. Those with aboriginal status had higher utilization rates (24.1%) than did non-aborigines (16.2%, P <0.05). In the relevant chronic diseases category, people with "diseases of the ear and mastoid process" (21. 2%) had a higher utilization rate, and utilization rate for those with cancer (13.1%) was less than those without cancer (16.5%, P <0.05). Regarding severity of disability, those with mild disability had the highest utilization rate (18.8%) (P <0.05).
Factors related to use of free adult preventive health care As shown in Table 2, this study found that gender, age, education, marital status, urbanization of residence area (URA), monthly insured payroll, aboriginal status, catastrophic illnesses status, relevant chronic diseases, and severity of the disability had significant effects on the use of free adult preventive health care by the physically disabled (P <0.05).
The logistic regression analysis showed that physically disabled men had a slightly lower free adult preventive health care utilization rate, only 0.82 times that of women (95% CI = 0.80-0 84). In the age aspect, using 40 to 44 year olds as a reference group, the 60 to 64 age group's utilization rate was 1.41 times greater than the reference rate (OR = 1.41, 95% CI = 1.34-1.48). The lowest rate was among those older than or equivalent to 70 years, which Those with aboriginal status had a higher utilization rate, which was 1.21 times higher than that of nonaborigines (OR = 1.21, 95% CI = 1.14-1.28). Those with junior college or university educations or above had a utilization rate of only 0.95 times that of those with elementary school educations and below (OR = 0.95, 95% CI, 0.91-0.99). Those who were married had 1.11 times the utilization rate (OR = 1.11, 95% CI = 1.07-1.15) of those who were unmarried. Those with a catastrophic illness/injury had a lower utilization rate, only 0.86 times (OR = 0.86, 95% CI = 0.83-0.89) that of those without catastrophic illness/injury. Relevant chronic diseases (except for cancer, diseases of the nervous system, and diseases of the urinary system, which had less utilization than those who were not afflicted), had a higher utilization rate than those not suffering from relevant chronic diseases. Those with "severe" disability had the lowest utilization rate among the severity of disability categories, which was 0.8 times (OR = 0.80, 95% CI = 0.78-0.83) that of the "mild" category.

Discussion
Comparing Taiwan's disabled people's utilization of free adult preventive health care, mental illness was the highest, being 1.47 times that of the physically disabled (OR = 1.47, 95% CI = 1.37-1.45); second was that of the hearing impaired (OR =1.22, 95% CI = 1.19-1.24), which was 1.22 times [16] that of the physically disabled. Compared to the free preventive health care utilization rate of all population (34.2%), the physically disabled had a much lower utilization rate (16.37%) [28].
This study found that women had a higher free preventive health care utilization rate than did men. This was consistent with the results of previous studies [29][30][31]. It is possible that women are more concerned with health-related messages, and therefore have a higher utilization rate [32]. For age, the group with the lowest utilization rate was the above-70 group. Whether this was related to elderly handicapped persons mostly living in nursing homes and other institutions [33] or because they have geriatric chronic diseases that cause them to frequently visit hospitals or clinics and not necessary for preventive care remains a valuable topic for future research.
For area of residence, the free preventive health care utilization rates among the physically disabled living in URA Levels 5, 6, 7, and 8 were higher than those living in Levels 1, 2, 3, and 4. Preventive health care utilization rates were higher in rural areas than in urban areas. Although urban areas have closer proximity to care, there are no designated personnel to encourage the public to conduct health checks. Rural areas have a slower pace of living, and people like to participate in free preventive health care with their neighbors. In addition, Taiwan's government has attached importance to the medical gap between urban and rural areas, regularly sending medical patrol vehicles to remote areas to provide medical care and to strengthen  publicity. Therefore, those in rural areas have higher preventive health care utilization rates than those in urban areas. Regarding socioeconomic status, previous studies have shown higher income earners have higher preventive health care utilization rates [34][35][36]. The study results showed that those with a monthly insured payroll higher than NT $15,840 (except for NT $48,200 to 57,800) have a higher utilization ratio than those earning less than NT 15,840, which was consistent with previous study results. Those with aboriginal status had a higher utilization rate than did non-aborigines. These results implied that since the majority of aboriginal people live in remote areas, the government assigns medical patrol vehicles to regularly provide medical care and preventive health care in remote areas, and then the aborigine's utilization rate was increased, which reflected the efforts of decreasing the health disparity between residents in urban areas and residents in remote areas. The utilization rate for education level decreased with increases in education. Those with junior college or university or above had the lowest rate. In recent years, various high-end, self-paying preventive health care programs have increased in popularity. Those with junior college or university educations or above and those with monthly insured payroll of NT $48,200 to 57,800 have been selecting these high-end, self-paying preventive health care programs because of their higher social economic statuses.
For marital status, married people had a higher adult preventive health care than did unmarried people. These results support the study conducted by Doescher et al. [29]. Married people tend to have more fixed residence and places of medical care than do unmarried people. They have more opportunities to become familiar with health care professionals and are more likely to accept preventive health care through their recommendations or to be informed by health care messages. In addition, married people have stronger social network (e.g., family members, relatives, and friends) support than do unmarried people, serving as a reminder for their healthpromoting behaviors [37,38]. For health status, those with a catastrophic illness/injury had a lower utilization rate than did those who did not have a catastrophic illness/injury. This result differed from that of the American behavioral risk factor surveillance system (BRFSS) [39]. Whether this was due to the physically disabled people's catastrophic illnesses/injuries making them weak and less mobile is unknown. Regarding the suffering from related chronic diseases category, those with diseases of the digestive system appeared most frequently. This was similar to the results that 58% or more of the patients suffered from constipation, onethird had regular abdominal pain, and 62% had irritable bowel syndrome in a 1998 study on spinal cord injury (SCI) [40]. Regarding the severity of the disability, the greater the level of severity, the lower the probability of preventive health care used. The finding is consistent with that in the study conducted in the United States (2004) [39]. The disabled individuals with higher severity of physical disability would highly depend on assistance of caregivers and leaded to low participation in the preventive health care.
Generally speaking, if the physically disabled people regularly receive free preventive health care, the disease could be early diagnosed and be early treated. If the disease is a minor problem, it could be improved through changes in health behaviors, lifestyle or diet pattern besides necessary medical care received. For the aged people with physical disabilities, if they have chronic diseases, they should visit physicians regularly to treat and control their illnesses. Both regularly receiving preventive health examinations and treating existent diseases are important for the aged and physically disabled people.

Limitations
In the present study, in order to understand the specific diseases or illness systems influencing the use of preventive health care among the physically disabled people, we included 15 types of chronic diseases as the variable instead of chronic diseases index such as Elixhauser. Thus, this study could not examine the relationship between uses of preventive health care and severity of chronic diseases. In addition, the database did not contain the lifestyle, health beliefs and behaviors of the participants, making further analyses difficult. These were the limitations of this study.