BJORL Population epidemiological study on the prevalence of dizziness in the city of São Paulo - PDF

Braz J Otorhinolaryngol. 2013;79(6): DOI: / ORIGINAL BJORL Population epidemiological study on the prevalence of dizziness in the city of São Paulo Roseli Saraiva

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Braz J Otorhinolaryngol. 2013;79(6): DOI: / ORIGINAL BJORL Population epidemiological study on the prevalence of dizziness in the city of São Paulo Roseli Saraiva Moreira Bittar 1, Jeanne Oiticica 1, Marco Aurélio Bottino 1, Fernando Freitas Ganança 2, Riva Dimitrov 3 Keywords: dizziness; epidemiology; prevalence. Abstract The epidemiology of dizziness is essential in clinical practice. Objective: To establish the prevalence of dizziness in the adult population of São Paulo, its clinical characteristics and level of discomfort. Method: A prospective cross-sectional study ran from April to October of 2012 by a field questionnaire, totaling 1,960 interviews. The predictor variables assessed were age, gender, type of dizziness and the dizziness disability index. The statistical tools used to assess the significance between variables were the chi-square test, Student s t-test and logistic regression. We used a 95% confidence interval for estimated values. Results: The prevalence of dizziness in the city of São Paulo was established at 42%. We found two peak of complaints, 49% in the range of years and 44% in the elderly. Vestibular-related dizziness was estimated to affect 8.3% of the population, mainly women (p 0.001). The symptoms caused disability in 27% of symptomatic interviewees and it is more bothersome to females (p 0.001), who more frequently seek medical care (p 0.001). Conclusion: The prevalence of dizziness in São Paulo was found to be 42%. It affects daily activities in 67% of symptomatic patients, but only 46% of them seek medical help. 1 PhD in Medicine; Assistant Doctor at the Neurotology Department HCFMUSP. 2 PhD in Medicine; Adjunct Professor of Otology and Neurotology at UNIFESP (Paulista School of Medicine - Federal University of São Paulo). 3 MSc in Medicine. Medical School of the University of São Paulo. Se d o espo de e to: Roseli Sa aiva Mo ei a Bita. Rua D. E éas de Ca valho Aguia, º, º a da, sala. Ce uei a Césa. São Paulo - SP. B asil. CEP: -. Tel: + -. Fa : + -. E- ail: oseli. ABORL-CCF FAPESP. Pape su ited to the BJORL-SGP Pu lishi g Ma age e t S ste B azilia Jou al of Oto hi ola golog o Ap il, ; a d a epted o August,. od.. 688 INTRODUCTION Body balance is fundamental in the life of the individual and it causes high anxiety to patients; gait difficulties; disorientation; social exclusion and isolation 1-4. According to the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology and Head and Neck, dizziness can be defined as any illusory sense of motion without any real movement in relation to gravity 5. The symptom may or may not have originated on the vestibular system, and it comprises sensations described in many different ways: dizziness (vertigo), imbalance, instability or fluctuation, pre-syncope or syncope, motion sickness, oscillopsia and falls. It happens at any age, from the first months of life all the way to old age 2,6-9. Non-vestibular dizziness are often poorly defined, usually described as malaise, dizziness, lightheadedness, feeling faint. They often represent symptoms of poor central nervous system perfusion and/or they may be associated with heart problems, postural hypotension, ischemic episodes or metabolism disorders 10. Central origin dizziness is often more insidious and less intense than those of vestibular origin. Dizziness epidemiology is of fundamental interest in clinical practice, especially among neurologists and otolaryngologists because the symptom is one of the 10 leading causes of visits to emergency services 11,12. It is estimated that 20% of patients seeking a general practitioner have some kind of dizziness 13,14 ; the third most common clinical complaint in a general clinic, second only to pain and fatigue 15. Dizziness prevails in females (1.3 to 1) and its incidence increases directly with age, peaking between 65 and 75 years 16, 17. A large percentage of dizziness spells are benign and undergoes natural compensation 18,19 ; however, it may be the first symptom of more severe cases, such as stroke or tumors. Numerous studies have shown that dizziness is one of the most prevalent complaints in medicine, affecting approximately 20% to 30% of the world population 14,20,21. However, its high prevalence in population surveys may be influenced by methodological biases, including how the questionnaires are applied, by conventional mail or Internet, or in how the symptom is described. A large epidemiological study recently conducted in Germany combined screening a large and representative population sample of 4,869 individuals with moderate to severe dizziness or vertigo, with the validation of these complaints through consultation with neurotologists in 1,003 of these individuals. The prevalence of vestibular-borne dizziness established for adults with ages 18 to 79 years was estimated at 7.4% (95% CI: 6.5 to 8.3%), and the frequency was three times greater in the elderly than in young adults 17. The study also showed that vertigo is recurrent (88%) and causes severe problems (80%) in most cases, with interruption of daily activities, leave of absence and frequent medical appointments 17,22. According to the latest IBGE census of 2010, the city of São Paulo has a population of 11,253,503 inhabitants. Its birth rate is 15.59/1,000, the elderly representing 12.53% of the population and an illiteracy rate of 3.18%. The annual per capita income is R$ 39,445.20, and 58.40% of the population graduate from high school 23. These sociodemographic characteristics provide the city of São Paulo with the same profile as the majority of European countries. The demographic transition process seen with the fertility decline and increased survival, directly influences the age structure of the population, which transfers to the elderly the responsibility for supporting themselves economically. Thus, the social demands of São Paulo have been changing and it becomes necessary to better understand this population so that we can develop more adequate healthcare policies 24. The public and private healthcare networks in the city of São Paulo have no data on the prevalence of dizziness. Thus, compilation, analysis and communication of such information may help outline the profile of the population. It starts with the assumption that the dizziness is a prevalent complaint in São Paulo, with potential morbidity and impact on people s health, particularly in the elderly. Thus, additional information about the frequency, determinants and associated comorbidities may improve primary care and guidance of patients in screening areas, in addition to provide foundations for public health policies and prevention campaigns. Moreover, risk factors collected from population samples may raise new pathophysiological hypotheses and help us advance in the treatment of dizziness. Determining the prevalence of dizziness will meet the need to know this information in the municipality, in order to implement projects involving the prevention and rehabilitation of the target population. Without a real estimate, it is impossible to plan any kind of action, including obtaining resources or support for these projects. This epidemiological survey aimed at: 1. Establishing the prevalence of dizziness in the adult population of São Paulo; 2. Describing the main clinical characteristics of dizziness in this population; 3. Quantifying the degree of annoyance the symptom caused to the population. 689 METHODS This cross-sectional study was carried out between April and October of 2012, in São Paulo, which has a population of approximately 11,253,503 inhabitants according to the most recent IBGE census of The population survey used to determine the prevalence of dizziness in the city of São Paulo was conducted through a questionnaire to the population, previously created for this purpose; adapted and modified from the original study to determine the prevalence of Meniere s disease in the population of southwestern Finland 21 and Disability Index 25. The project was conducted in accordance with the standards and guidelines established by the ESOMAR International Code of Practice for Social Research and Marketing, and after approval by the Ethics Committee for Analysis of Research Projects, research protocol #: 0970/09. The project received funding from the Brazilian Association of Otorhinolaryngology and Facial and Neck Surgery (ABORL-CCF), through the bidding process used to grant scholarships for epidemiological projects and also the Foundation for Research Support of the State of São Paulo (FAPESP/Regular Support to Research/Process #: 2011/ ). Sample Based on population studies, the sample size was calculated assuming an expected 10% prevalence of dizziness in the population, with an accuracy of 2%, confidence interval of 95%, design effect of 2, and 10% increase for possible losses. The initial sample size was calculated at 1,901 inhabitants. Estimating 3-4 people per household, for a total estimated number of 633 households visited. It is expected that 40 of the 13,193 census districts in São Paulo were randomly selected, eight in each of the five regions of the city (north, south, east, west and center). The five regions were included to ensure sample diversity, thus ensuring an estimate for all walks of life and age groups. The random selection of the census district was proportional to the population size of the region, to maintain equal likelihood. Data collection We used cluster sampling among the different census districts. In order to select the households to be visited for data collection, we randomly selected the census districts. Within each of those districts, we randomly selected one block and a corner of this block. From this corner selected, we consecutively visited the first 16 homes. A specialized company, with large experience in this field - Analítica Pesquisas Mercadológicas, Sociais e Econômicas Ltda - every adaptation and encoding of the population structured questionnaire; pre-tests; prepared the cards; field manual and control material; team training; random selection of the census districts; fieldwork; personal interviews at home and statistical analysis of the results collected. Inclusion Criteria We included individuals aged 18 years and of both genders. In the population sample, all dwellers of each household selected were interviewed, after agreeing with the terms and signing the consent form. When there were two or more families in the same plot, each was considered separately. Exclusion Criteria We used the following exclusion criteria vis-à-vis the homes selected: (1) residents who were not home after three attempted visits, (2) those who were sick and recovering, (3) non-residents in the home that was being visited among them the relatives and/or friends and maids who do not dwell in the house, (4) commercial houses where no one lived and empty houses. Study variables The extent of occurrence was evaluated by the ratio between the number of individuals with dizziness in relation to the total number of interviewees. The main predictor variables evaluated were gender, age, education, occupation, race, defined as qualitative variables. Quantitative variables included the degree of dizziness discomfort as measured by the Disability Index 25. Statistical Analysis The variables investigated were subjected to descriptive analysis. The significance of the association between qualitative variables and the extent of occurrence, presence of dizziness, was established by the chi-square (χ 2 ). For quantitative variables we employed the Student s t-test. The variables that showed significant association with the extent of occurrence (p less than 0.05) were subjected to a logistic regression model to identify possible confounders of the association and to identify the factors most strongly associated with the presence and severity of dizziness. We also calculated the 95% confidence intervals for the estimates produced (e.g. prevalence of dizziness). 690 RESULTS Sample The company responsible for the field survey chose to expand the sample size initially calculated at the time of collection, to reduce possible losses. Therefore, our final sample consisted of 1,960 individuals. To obtain this number, 1,008 households were visited, 63 randomly drawn among the 13,193 census districts in São Paulo, which accounted for an average of 2.2 adults per household (Table 1). Table 1. Sample size (n) and percentage (%) of households visited according to the census of the city of São Paulo. Areas n: Sample size; % Percentage of the sample. Total n % East South North West Center Sample Base The descriptive analysis of the main predictor variables assessed (gender, age, education, occupation, race) is itemized on Table 2. Prevalence of symptoms in the population of the city of São Paulo Dizzy feeling The dizzy feeling complaint prevalence among the population of the city of São Paulo was 42% (831 subjects) versus 58% (1,129 individuals) who denied this complaint. The symptom affects a greater percentage of women (52%) compared to men (31%). Application of the Person s chi-square test revealed statistical significance (p = 0.048) in the evaluation of dizziness reported by the age groups. The age-wise trend is one of fluctuation with complaint peak (49%) in the range of years (Table 3). Dizziness description To better organize the answers in item: how would you describe your dizziness we have a list containing four possible descriptions of the symptom for the respondent to indicate the phrase that best defines his/her feeling. The most common and most often stated was vertigo (a feeling that either the body or the environment is turning), in 41% of the 831 subjects asked. Second, floating (sensation of lightheadedness, void head, heavy head), stated by 27% of respondents. Thirdly, fainting sensation (feeling of Table 2. Descriptive analysis of the proile of the sample collected for the city of São Paulo. Gender Age Schooling Race (Per observation) n % Females Males / / / / / e Refusal 3 * Illiterate/Incomplete basic education Complete basic education/incomplete junior high school Complete junior high school/incomplete senior high school Complete senior high school/incomplete higher education Complete higher education Whites Blacks Yellows 45 2 Browns Indians 4 * Sample Base n: Sample size; % Percentage of the sample; * Percentage value lower than 0.003%. impending fainting, usually with vision loss or vision blurring), with 18% prevalence. And finally, imbalance (difficulty in maintaining posture engaging the body), reported in 14% of the cases. The imbalance complaint, reported by 14% of the symptomatic population, increased to 24% in the range of more than 65 years, demonstrating a significant increase (p = 0.017, Pearson s Chi-square test) of prevalence with age (Table 4). Table 4 is the type of dizziness in relation to age. Vertigo is more prevalent in the younger age group (reaching 49% of respondents aged between 18 and 25 years). The imbalance grows continuously with age, peaking in individuals over 65 years. Dizziness-related nausea Most respondents (69%), never had nausea associated with feeling dizzy. The distribution of responses can be seen in Graph Table 3. The dizzy feeling complaint prevalence according to the various age groups in the population of the city of São Paulo. Have you ever felt dizzy? Total 18 to 25 years 26 to 35 years 36 to 45 years n: Sample size; % Percentage of the sample; DF: Difference; p: Statistical signiicance (two-tails); a: 2 cells (14.3%) expected count less than 5. The minimum expected count is Age 46 to 55 years 56 to 65 years Over 65 years n % n % n % n % n % n % n % Yes No Sample Base Chi-squared test Value DF p Pearson s chi-squared a 6 0,048 Odds ratio 13, ,032 Linear by linear association 1, ,259 Table 4. Distribution of the various descriptions of the feeling dizzy complaint (n = 831) according to age groups in the population of the city of São Paulo. How would you describe your dizziness? Total n: Sample size; % Sample percentage; * Individuals with dizzy feeling; DF: Difference; p: Statistical signiicance (two-tailed); the: 0 cells (0%) expected count less than 5. The minimum expected count is Age 18 to 25 Years 26 to 35 Years 36 to 45 Years 46 to 55 Years 56 to 65 Years Over 65 Years n % n % n % n % n % n % n % Vertigo Fainting Unbalance Fluctuation Reduced Base* Chi-square test Value DF p Pearson s chi-square 28,842a 15 0,017 Odds ratio 28, ,021 Liner by linear association 5, ,017 Analyzing the subgroups, 83% of men reported never having nausea-related dizziness, against 61% of women (p 0.001, chi-square test). With respect to age, absence of nausea associated with dizziness tended to be more prevalent (79%) in young individuals - aged years, despite the fact that the difference between age groups was not statistically significant (p = 0.110, Pearson s chi- square test). Frequency at which of dizziness happens To better organize the answers to this item, we presented a list of eight possible rate of symptom occurrence, for the respondent to indicate the one that best describe his/her situation. Graph 2 depicts the distribution of responses. The reported incidents of minor importance with respect to the frequency (it only happened once or less than once per year) were mentioned by 18% and 7% of respondents, respectively. Most respondents (46%) reported having symptoms one to 12 times per year. As the frequency of dizziness increases, the number of cases decreases, until reaching a frequency of 1% of respondents who stated 692 older individuals, when compared to younger patients. We also realized that more than half of the patients (59%) had been having dizziness spells between zero and three years. Graph 1. Prevalence of nausea associated with feeling dizzy (n = 831) in the population of the city of São Paulo. Graph 2. Distribution of the frequency of occurrence of symptoms among those who report feeling dizzy (n = 831) in the population of the city of São Paulo. feeling dizzy all the time. As far as the subgroups are concerned, the frequency tended to fluctuate much, but we noticed that among the younger, feeling dizzy tends to be less frequent than among the elderly. This difference was statistically significant (p 0.001, chi-square test). In addition, all age groups had dizziness spells peaking between 1x per year and 1x per month. How long they had been feeling dizzy The analysis of the item: how long have you been feeling dizzy (question 21 in Annex 1), had a large variation in disease progression time as per reported by the respondents. Reports ranged from less than one year (a few months) to over 30 years; this variability hampered the search for an analysis parameter. We have compiled the responses into time slots that helped us better display the content (Table 5). We noticed that, when applied to age groups, the chi- square test was statistically significant (p = 0.001) vis-à-vis the results (Table 5), with higher prevalence of long standing dizziness among Level of disability caused by dizziness In order to investigate the level of discomfort caused by dizziness, we presented the respondent with a list of six possible descriptions, based on the Disability Index 25, so that he/she could indicate the phrase that best described his/her situation. The first two sentences (1 = symptoms are negligible, do not bother and 2 = symptoms bother you, but without causing disability) were the most frequently mentioned, by 33% and 40% of respondents, respectively. The third sentence (the symptoms bother you, cause mild disability, you do the usual tasks (work, home), but the symptoms interfere with activities outside the home), which describes mild disability, was reported by 14% of respondents. The fourth phrase (the symptoms bother you, cause moderate disability, interfe
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