The Number of Centenarians in Brazil: Indirect Estimates Based on Death Certificates
Gomes, Marília Miranda Forte, Turra, Cassio M., Demographic Research
The Brazilian population is rapidly aging. As a result, the number of centenarians has grown steadily, about 77 per cent between 1991 and 2000. Although expected, the increasing number of centenarians may be exaggerated by data quality issues. We compare the recorded centenarian population in the 1991 census with indirect estimates based on the extinct generation method. We find three times more people in the census than according to the indirect estimates. Uncertainty about the true size of old-age populations has important implications in data-deficient countries, particularly in the estimation of adult mortality.
According to census data, there were 24,576 centenarians living in Brazil in the year 2000, about 1.8 times more than in 1991 (IBGE 1991, 2000). The United Nations projects the centenarian population will keep increasing rapidly, almost sevenfold by 2050, when it will reach 160,000 people (United Nations 2007). These figures are not necessarily surprising when compared to those from populations where the demographic transition started earlier. In the last 50 years, the population above age 100 has grown very fast in Canada (Bourbeau and Lebel 2000), France (Vaupel and Jeune 1995, Vallin and Meslé 2001), the U.S. (Krach and Velkoff 1999, Kestenbaum and Ferguson 2005), and in many other countries (Human Mortality Database 2008).
High fertility levels in the past (Frias and Carvalho 1994; United Nations 2007) combined with fast declining mortality rates at older ages (Campos and Rodrigues 2004) have certainly allowed a much larger number of people to survive to the age 100 and older in Brazil. However, we remain skeptical about the population counts reported by the Brazilian census bureau. At older ages, data are beset with a variety of problems in many populations (Coale and Kisker 1986, Kannisto 1988, Coale and Caselli 1990, Preston, Elo, and Stewart 1999, Thatcher, Kannisto, and Andreev 2002), and there is no reason to believe these errors are absent or less frequent in Brazil. Indeed, a simple inspection of the ratio of the population aged 100 and older to 85 reveals notable discrepancies between Brazil and other selected countries of presumably higher quality data (Table 1). For example, in 1991, there were 16 centenarians per 100 people at age 85 in Brazil, eight times more than in Sweden. While comparing relative cohort sizes across populations can be misleading, because of differences in fertility and migration rates, the disparities are large enough to suggest a possible overstatement of age in the Brazilian census data.
In this article, we evaluate the quality of the census data by comparing the recorded centenarian population in the 1991 census with indirect estimates based on the method of extinct generations. The question studied here is not only relevant because Brazil is a large and rapidly aging country, but also because it reveals inconsistencies between deaths and population counts that have implications for the estimation of adult mortality in data-deficient countries.
Our approach follows the method of extinct generations to reconstruct the centenarian population from cohort mortality data (Coale and Caselli 1990; Elo and Preston 1994; Bourbeau and Lebel 2000, Thatcher, Kannisto, and Andreev 2002). Assuming international migration is negligible, we accumulate the number of cohort deaths to persons at ages above 100, from 1991 to 2006, to estimate the number of centenarians by sex, as of January 1st of 1991.
Deaths come from the Mortality Information System of the Ministry of Health (SIM/Datasus). The SIM is a database that contains information about persons who died since 1979 in Brazil. Because the data are available only by age and period, we assume deaths to be distributed evenly by time of occurrence and decedent's age to calculate cohort deaths at each age-period. Earlier studies that were based on indirect methods suggest that 13 and 17 percent of deaths were missing from the SIM, respectively for adult men and women, on average, during the 1990-2000 period (Paes 2005). …