Longevity and Health: Trends in Functional Limitations and Disability Among Older Adults in Portugal, 1985–2005

This research aimed to analyze trends in functional autonomy of the Portuguese population with 65 years and over, between 1985 and 2005 and find the variables that best explain disability. Data sources comprise the four National Health Surveys (NHS) undertaken so far in Portugal (1987, 1995, 1998, 2005). The study is descriptive and correlational. A regression model was constructed to explain a disability index that was built from the variables related to functional autonomy included in the 2005NHS. There was a negative Compounded Annual Growth Rate (CAGR) between 1987 and 1995NHSs and 1998/2005NHSs (−2.67 %) but between 1995 and 1998 the CAGR was positive (3.12 %). Variables that explain disability were age, sex, education, income, chronic diseases and self-perception of health status.. In the timeframe considered by the NHS authors found no defined trend in the prevalence of disability. The underlying reasons may be related, on the one hand, by the improvements in the living conditions of the Portuguese population from the 80’s but, in the other hand, this fact led to a progressive increase of the cohort with 85 years and more, much more vulnerable to chronic diseases.

for old age (Fried and Bush 1988). These models must address the prevention of chronic diseases and foster behavior that stimulates the maintenance of autonomy (Gill et al. 1997).
The positive changes that took place in health indicators in Portugal were reflected in the growth of life expectancy at birth, women 83, men 77, (OECD 2013) in spite of the fact that the difference in life expectancy in relation to EU countries has grown. Improvement in life expectancy, especially in the older age groups, is not normally associated with significant reductions in morbidity. In fact, increased longevity has become more generally associated with chronic illness or other disabilities requiring more medical services and other forms of personal care (Santana 2000).
In Portugal, women live longer than men, but women appear to live in a poorer state of health with a shorter disability-free life expectancy and lower self-assessed health status than men. Life expectancy is shorter in the less populated and less urban regions of Portugal (WHO 2010).
Our main research question is as follows: Given that the demographic model in Portugal has been characterized by the increase in longevity what was the evolution of disability in the Portuguese elder between 1987 and 2005?
The information is analyzed and presented from a descriptive and correlational form and a regression model is also addressed, namely for how far a set of variables explain a disability index constructed from the database of the 2005 National Health Survey (NHS).
The following objectives were defined: a. Characterize disability in the Portuguese population aged 65 years or more between 1987 and 2005; b. Analyze the trends of disability between 1987 and 2005; c. Identify the variables that best explain disability using the last NHS data.

Material and Methods
Our main sources are taken from the NHS, kindly provided by the Portuguese National Health Institute. The NHS is an instrument to measure how the Portuguese population perceives their own health; it generates estimates for health and disease in the Portuguese population, as well as their determinants, and also allows the study of its evolution over time. The NHS are currently the only representative source of information that draws a profile of Portuguese health..It is a self-perceived assessment summarizing how each individual feels about his/her health and not the objective health condition revealed by measurable indicators of organic functions. Also the questions related to the performance of the AVDs were registered regarding the individual's self perception for their performance. The results are not sampling values, but concern the whole resident population through the application of a mathematical method that expands the individual responses taking into account the age and sex composition of the inhabitants. Information was gathered through face-to face interviews.
Notwithstanding, that self reported health is one of the most important indicators when characterizing the individual's functional competence to perform daily living tasks that relate to autonomy and self-determination. Moreover, as a subjective indicator, it may complement information from other more objective health factors such as mortality and morbidity. According to Fernandes (2007), a causal relation can be established between this indicator of subjective evaluation and the individual's health. It is also important to note that the NHSs do not cover the institutionalized elderly which may subvert data regarding the prevalence of dependency among institucionalized older people. European studies (EC 2004;Rohrbasser 2008) using health surveys conducted in several countries state that excluding the institutionalized population from these studies impedes the characterization of the elder's health profile as the people with most health problems and greatest dependence levels are excluded from the analysis.
Considering the NHSs, of the total cases, the respondents who were aged less than 65 years were excluded and analyzed the resulting sample. The percentage of individuals 65 years and more over the total was 15.6 % in 1987 from 19.1 % in 1995 from 20.1 % in 1998 and 21.1 % in 2005 which shows the ageing demographic trends Table 1.

Results and Discussion
According to the NHS, the percentage of people in the total population aged 65 years or more increased from 15.6 % in 1987 to 21.1 % in 2005; this is in line with Eurostat and OECD (Eurostat 2006;OECD 2009).
As for health, the analysis covered chronic diseases and long-term disabilities. As the design and content of the four surveys varies, it is difficult to establish a comparative analysis for every variable Table 2.
The self-perception of health is not included in the first NHS, therefore, only the last three surveys were analyzed in relation to this variable. Answers indicated that the large majority perceived their health to be "reasonable" or "bad". However, a percentage of people referring to "good" health rose significantly (from 6.5 % in 1998 to 10.7 % in 2005). According to Santana (2005), the proportion of the population referring to their health as bad went from 70 % in 1995 to 58 % in 1998. In both cases, women's assessment of their health was more negative. Moreover, the Portuguese population's perception of their health was worse than the EU15 average.
Although the four surveys cover several types of chronic disease, the analysis focused only on variables that may generate disability due to the associated risk. Cardiovascular diseases, diabetes, respiratory diseases, osteomuscular diseases, osteoporosis, depression, tumors and eye diseases, apart from dementia, are mentioned by   Inzitari et al. 2006). Smoking is also mentioned as a risk factor, both for the selfperception of health and changes in motor function (AIHW 2000;Santana 2005). According to our research objectives, the analysis focused on answers regarding diabetes, hypertension, pain (persistent pain is considered an important predictor of disability, given its interference in the musculoskeletical system (Kerns 2006) rheumatic diseases, osteoporosis, stroke, glaucoma and retinopathy, tumors, renal diseases, anxiety, wound, respiratory diseases (emphysema), obesity, depression and heart attack. All these chronic diseases are covered by the 2005 NHS and were introduced in a multiple linear regression model, in conjunction with other variables to explain disability levels. Final results exclude hypertension, eye diseases (glaucoma and retinopathy), tumors, renal diseases, depression, heart attack, wound and anxiety from the model because they do not show statistical significance. Data concerning hypertension, diabetes and pain are referenced in the 4 surveys, which allowed for their comparison. Hypertension is a chronic disease and is not a direct cause of incapacity. However, it is an important risk factor for cardiovascular diseases, which is mentioned by a high percentage of respondents (approximately 50 %), and increased substantially between 1987 and 2005 (43.7 % to 50.4 %). The average age in which the respondents mentioned becoming aware of the disease increased slightly between 1987 and 2005 (58.5 % to 58.9 %). This may reflect two aspects: the progressive increase in the number of people suffering from hypertension (impacted by unhealthy habits) and at greater risk of cardiovascular diseases, or a more preventive diagnosis of the disease. Although diabetes is less prevalent than hypertension, a similar situation also occurs as the number of individuals referring to the disease rises with each of the four surveys. The average age for diabetes is slightly higher than for hypertension and there are also slight differences in the period considered between the four surveys (60.3 to 61.2 years). Back pain associated to postural changes and degenerative alterations of the musculoskeletical system, which also affects the performance of ADL (Inzitari and Basile 2003;Inzitari et al. 2006), is referred by a high percentage of individuals, and increases considerably between 1995 and 1998 (56 to 65 %). The average age for this is 13 years older in the 2005 survey that in 1998. The percentage of individuals mentioning chronic back pain is much lower in 2005 (8.8 %), but this seems to be related to the way in which the question is asked (chronic or persistent) and therefore makes the results incomparable. Strokes, which have marked effects on autonomy (Edwards 2001), are mentioned by 6.2 % of respondents in 2005 and the average age of appearance is 67.5 years. The assessment of chronic disability covers a set of competences that are framed in the ADL and IADL. The 1987 NHS considered a small number of variables for this purpose; the 1995 and 1998 surveys include a larger number of variables that assess autonomy. The 2005 NHS is the most comprehensive survey, despite excluding some important matters as sphincter control. The vast majority of scales for assessment of performance in ADL and IADL consider sphincter control an important indicator of disability (Mahoney and Barthel 1965;Lawton and Brody 1969;Katz 1983) and also preponderant to the risk of institutionalization (Richard et al. 2004). The dimension of the survey related to long-term disability reveals that 87 % of disability situations are caused by disease in the following order of importance: heart attack (38.7 %), osteoporosis (16.7 %), depression (8.1 %), strokes (6.2 %) and obesity (3.5 %). The assessment the ADL performance covered a set of tasks that can profile the dependence of the older people. The number of individuals that answer affirmatively to the question "am always in bed" oscillates between 2 % and 3 % in the period under analysis. This increase may point to a rise in the number of dependent individuals. The question assessing the respondents that are limited to a chair reveals a small percentage of people in these conditions. This question was not asked in the 1987 NHS and appeared only from 1995 onwards. There is also a slight rise in the percentage of individuals with no autonomy and dependent on a caregiver over the three NHS (0.9 % in 1995 to 6.2 % in 2005). There is little change in the percentage who are able to get out and sit on the bed or chair (on average, approximately 75 % of the individuals are able to do this without difficulty) in the periods under analysis, with a greater disparity between the 1987 and 1995 NHS (55 % with total autonomy in 1987 vs. 77 % in 1995). The answers to these questions reveal a slight increase in totally dependent individuals potentially suffering from severe disability. According to Jacobzone et al. (1998), about 5 to 8 % of the elders residing at home are completely dependent on others to maintain their basic levels of daily living.
The ability to execute daily living tasks are interrelated with the performance of physical functions and their integration in more or less complex activities; these range from specific movements like walking, or going up and down stairs to more integrated activities that contribute to the performance of social roles (Suthers 2004). The NHS question that refers to the ability to walk discriminates several levels of difficulty. Data show that a large percentage of respondents do not exhibit any type of impediment in walking. The percentage of individuals able to walk unaided rose significantly from 53.7 % in 1987 to 75.4 % in 2005. Of all the assessed tasks, walking related functions have the most positive results throughout the four surveys. The progress is similar for "going up and down stairs", also related to the ability to walk,, with 33.5 % able to do this unaided in 1987 vis-à-vis 58.3 % in 2005. The more positive evolution of these tasks may be related with the advances in and increased access to knee and hip surgery and walking devices, which have made an important contribution to the independence of the elders. On the other hand, mobility has always been a serious issue for the loss of autonomy. A research by Jagger et al. (2001) states that there is a functional decline in the inferior extremities long before superior extremities, thus limiting walking and movement. Activities related to "using the toilet" and being able to perform "daily hygiene" are included on all mainstream ADL scales (Mahoney and Barthel 1965;Granger et al. 1986). The question related to "using the toilet", assessed in the last three surveys, shows a deterioration from 85 % able to use the toilet unaided in 1995 to 81 % in 2005. The ability to go to the toilet remained almost unchanged in the 3 surveys (90 % of the elders perform the task) but there was a slight decline in the percentage able to do so completely unaided. The 2005 NHS excludes from this question the respondents that are able to take a bath autonomously (about 83 %). According to the "hypothesis of environmental docility", formulated by Lawton and Brody (1969) to express the relation between environment and competences, barriers to using the bathroom for daily hygiene are one of the greatest difficulties faced by the elders. With an increasing number of people showing difficulties walking alone to the bathroom, slight changes in this access may lead to more and better autonomy (Crews and Zavotka 2006). As for the "ability to dress and undress", we can conclude that although the respondents generally maintain the ability to do this autonomously (from 86 % in 1987 to 74 % in 2005), the percentage with difficulties has increased in the last three surveys; this is also the case for the variable assessing the ability to "pick up objects from the floor", (an essential activity when living alone). The ability to "grasp" (pick up small objects) is only assessed in the 2005 NHS, this shows that around 72 % of the respondents have no difficulty with this task. Data show also that a large percentage of respondents eat and drink autonomously (96 % in 1987 and 89 % in 2005). However, the percentage of dependent individuals in this particular task has increased over the last three surveys. A research by Jagger et al. (2001) indicates a late decline for superior extremity dexterity, although severe motional and cognitive dependence may influence autonomy when "taking food to the mouth".
The ability to perform IADLs (use public transportation, go shopping, clean the house and prepare meals) is only discriminated in the 2005 NHS. About 75 % of respondents are able to use public transport without difficulty. The transport networks impede social isolation and are vital to quality of life.
About 75 % of respondents state they shop completely autonomously. On the other hand, 36 % of individuals need some kind of help with housekeeping related tasks and 74 % no problem preparing meals. According to Crews (2005), many of these tasks could be facilitated by adjusting the environment to the individual's abilities; the use of simple technology could yield important results for autonomy and keeping the elders in their own homes. Hearing is assessed in the last three NHS; the results show that around 80 % have no difficulty hearing though this was lower in 1998 (76 %) and the previous surveys. Although not a fatal disability, both hearing and visual impairments affects the way in which people function (Richard et al. 2004). When the impairment is combined (hearing and visual), there is a double risk of restricted activity (Jagger et al. 2005). Although the situation for visual impairment is similar to that of hearing, it is more stable over the last three surveys (nearly 90 % of the elders have no visual difficulties). The results do not show a decline in the prevalence of visual disabilities despite the better access to cataract surgery, according to several authors, this has improved the independence of the elders (Fries 1998;Richard et al. 2004). "Sphincter control" is not assessed in the 2005 NHS, as mentioned above; however, there is a striking increase from 76 % stating perfect control in 1987 to 87 %, in1998. In 1998, the percentage went down to 82 %.
The question assessing physical activity is formulated differently in the four NHS, so the following description refers only to the 2005 survey. Data obtained reveals that only a small percentage of respondents do regular physical activity (around 2 %). Several authors emphasize the positive impact of physical activity on overall health, and also on delaying disability and the likelihood of recovery (Fries 1998(Fries , 2002Vass et al. 2002;Heikkinen 2003;Ofstedal and Herzog 2003;Graciani et al. 2004;Dunlop et al. 2005). Respondents are asked to define their household income according to tax groups.. In 1987, more than 50 % placed themselves in the first two lowest tax groups. In 2005, most respondents were in the 3rd, 4th and 5th tax groups and only a very small percentage in the 1st segment. Although improved living conditions allowed many elderly to benefit from greater income, this population is still very vulnerable to poverty which is prevalent in Portugal among the elders, people living alone and, most importantly, living in a rural environment. According to Portuguese Statistics (INE 1999), the clusters that included the elders had a significantly lower income than those that did not, when compared to national average. Questions on quality of life are only included in 2005; most respondents indicate it is "neither good nor bad" or "good". The concept of satisfaction with life, physical and social well being and psychological condition come under the concept of health defined by WHO (Bowling et al. 2002).
A theoretical model was developed to explain dependence levels based on data from the NHS, and which was in keeping with previous studies reviewed in the scope of this research. Firstly, it was important to understand how disability has evolved during the study period. As the assessment of the disability in the NHS does not result from a weighted index for reporting the performance of the subject, each task was therefore analyzed according to a dichotomous variable' performs task without help and without difficulty "or, alternatively, 'does not perform the activity or performs with difficulty". A composite variable, the Global Disability Indicator (GDI), was constructed from this analysis, this represents the sum of all tasks that respondents do or do not perform. All subsequent 2005 NHS analyses were complemented using this global indicator. The number of individuals who reported having no kind of disability evolves positively from 1987 (25.5 %) to 2005 (37.9 %), although the trend is not linear as the value rises to 40 % in 1995 down to 34.2 % in 1998, rising again to 37.9 % in 2005. One interpretation should be made in these indicators; the number of individuals with long-term disabilities assessed in 1987 was substantially lower than in the following NHS and these data should be assessed in line with this assumption. However, the existence of a disability determining, in most cases, the existence of other. The fact that the evaluation of some activities in the first surveys are not present does not mean that the overall analysis is still not possible. According to the analysis of disability per survey and the percentage of respondents who are not able to accomplish the tasks, there is a clear improvement for the functions related to gait (walking and climbing stairs) and sphincter control; however, the data also suggests an increase in the percentage of severely disabled (bed-ridden and dependent on feeding for instance). The figures obtained for the proportion of older people with disabilities through the Compound Annual Growth Rate (CAGR). The CAGR, which is an arithmetic formula used to compare year-over-year growth rate of a phenomena over a period of time indicates that the evolution of the percentage of older people with disabilities is not linear and there is no clear trend in the period under study. The CAGR for the percentage of elderly with a disability was −2. 67 % between 1987 and 1995, 3.12 % between 1995 and 1998 and between 1998 and 2005 −0.82 % (Table 3).
The design of an analytical model to explain disability was based on other studies which sought to identify factors that affect the onset of chronic disability and decreased autonomy (Klaassen-van den Berg Jeths and van Langen 1990; Kunkel and Applebaum 1991;Moody 1994;Schulz 2003;Robine and Michel 2004). A multiple linear regression model was sued in the present study using (GDI) as the dependent variable which is the sum of activities that subjects are unable to perform. The choice of explanatory variables was based on the literature review and thus introduced the following variables into the model: chronic diseases, smoking habits, number of visits to the GP, sex, age, marital status (living arrangements), education level, income level and self perception of health status.
It is known that after a certain age, almost everyone is clinically diagnosed with one or more disease, mostly chronic, which lead to difficulties in performing daily life activities. The visits to the doctor reveal how preventive actions in health care are implemented and its effect translates into lower levels of disability and dependency (AIHW 2000). The differences between men and women and the prevalence of disability in each are also relevant factors. Some disabling diseases, including cardiovascular disease, musculoskeletal conditions, anxiety and depression, contribute to more disability and decreased quality of life among women than men (Murtagh and Hubert 2004;Camargos et al. 2005). The effect of marital status (living arrangements) on the health of older people has been the subject of some studies (Rohrbasser 2008). There is consensus that married people are healthier and that disability is less prevalent among the married than among the widowed, single or divorced. However, this study found no relationship between marital status (or living with someone conjugally) and the GDI.
This study also examined the education level, associated with socioeconomic resources, as a determinant of health and disability. According to Fernandes (2007), social inequalities in access to education and socio-economic resources can be translated into different ways of managing health and are registered in the organs and systems. A study conducted by Heikkinen (2003) shows the importance of socio-economic resources in carrying out activities of daily living. The author concludes that more economic resources correspond to greater autonomy. The study by Minicuci and Noale (2005) suggests that levels of education and access to information translate into lower levels of reliance and this is  (Vaupel et al. 1998;Waidmannn and Manton 2000;Vita et al. 2003).
In addition, family support and social networks as well as the perception of health status are predisposing factors for dependency (Inzitari and Basile 2003;Coppin et al. 2006). The model variables relating to social support and environmental barriers were not included because they were unavailable, these could increase the model's response to the variation of the dependent variable.
The analysis of the standardized regression coefficients allows us to conclude that age, self-perception of health status, sex, income, educational level, the number of visits to the GP, emphysema, obesity, diabetes, osteoporosis, rheumatism, pain and stroke best explain the dependent variable (GDI). Some chronic diseases, anxiety, depression, smoking habits and marital status were not significant. The final adjusted regression model is significant and explains 32.4 % of the variation of the dependent variable, GDI (F (19, 2171) = 56.198, p-value<0.001; R 2 a =0.324) ( Table 4).

Conclusions
In the coming years, individuals who reach old age will be much more numerous than in previous generations. The baby boom generation will live longer due to the decline in the mortality rate over the life cycle. Societies must therefore be prepared to reflect and decide about social protection systems, retirement age, the living condition of older people as well as on ways to meet their needs whilst maintaining the sustainability of public finances. The ageing population requires different and more specialized care as some disease are becoming more chronic and less fatal thanks to scientific progress. Society has sought to provide the necessary support for the older people in order to maximize autonomy and independence, so that ageing takes place within the family and community for as long as possible,.
Although many people remain in good health after the age of 65, there is a growing risk of physical or cognitive disability as time progresses. The need for care depends on the individual's health (genetically determined or derived from unhealthy behavior) and personal and environmental limitations that stem from this. It order to understand all these factors, the NHSs databases were analyzed to characterize the profile of disability of the Portuguese elderly and the evolution of the prevalence of disabilities from the first NHS in 1987 to the last conducted in 2005.
The analysis of permanent disability based on the four NHS is complex due to variations in the number and formulation of questions. We tried to find lines and common trends in the questions especially in relation to the assessment of the activities of daily living performance.
Although there was not a general improvement in ADLs where there was a prevalence of disability, ADLs related to gait (walking, climbing and descending stairs) have clearly improved.
There is also a visible increase in the number of elderly confined to bed and also unable to feed themselves. Whereas major scientific advances are addressing problems associated with the lower limbs or reducing barriers to the docility of the environment, the increase of the percentage of elderly that cannot perform basic activities is evidence of a higher prevalence of severe disability in line with the growing segment of the older people.
Of the total elderly population in the 2005 NHS, 37.9 % did not indicate any kind of disability. When comparing the percentage of individuals with at least one disability in the last two surveys, we find an average decline of 0.82 % per year; this is in line with international trends that show a decrease in the prevalence of disability. It is therefore important to understand what type of variables may or may not be manipulated in order to leverage this trend. The multiple linear regression shows that certain chronic diseases, self-perception of health status, sex, age, education and income have a significant effect on the levels of disability. Self-perceived health status and age best explain the variation in the number of disabilities-even more than chronic diseases. Cultural limitations and socio-economic conditions, e.g. income, play a significant role in the analysis model; this therefore suggests that functional outcomes will improve if illiteracy declines. Further, it should be noted that the ability to react to an organic limitation may vary from one person to the other. Understanding in what extent the perception of health status results from idiosyncratic aspects and/or lack of confidence in institutions and the extent to which this can be modified to alter the pessimistic view Portuguese people have of themselves would therefore contribute to improving the level of disability and dependence.
In relation to chronic diseases, pain is a major factor for not performing activities and loss of independence. As it is not objectively a disease, It is therefore necessary to control the symptoms.
In Portugal, demographic trends point to an ageing population over the coming decades and the relation between longevity and health is a legitimate concern. By analyzing the various sources of information, this study reveals that there is not a clear trend in the improvement of health of older people. However, some characteristics of the younger generations that affect health status in old age are different from those of previous generations in terms of socioeconomic conditions and education levels.. As these people are the old of the future, we can foresee scenarios in which longevity will be accompanied by better health and less need for care.
This study allows us to compare the evolution of self-perceived disability in the Portuguese older population over five NHS. This study presents strong points sustained by a high number of cases which validates its results. Nevertheless the institutionalized population is not included which currently represents about 5 % of the older population in Portugal. This issue could give another dimension to the results and should be considered in future studies.