Osteoporosis Int (1992) 2:269-273 © 1992 European Foundation for Osteoporosis
Osteoporosis International
Original Article Differences in Fracture Pattern Between an Urban and a Rural Population: A Comparative Population-Based Study in Southern Sweden B. J6nsson 1, P. Gfirdsell 1, O. Johnell I, I. Redlund-Johnell 2 and I. Sernbo ~ Departments of ~Orthopaedics and ZDiagnostic Radiology, Maim6 General Hospital, Malm6, Sweden
Abstract. Differences in the incidence of hip fractures have been reported between urban and rural areas. In this population-based study the characteristics of fracture patterns between the city of Malta6 and the nearby rural district of Sj6bo were compared. A total of 782 individuals in Malta6 and 486 in Sj6bo were invited to participate. Fracture history for all invited was registered. The odds ratio for fracture was higher in Malm6, particularly for women over 70. More than half of the urban women aged 70 had a history of a fracture. A fourfold increase in fracture prevalence between the ages of 60 and 70 was observed in women in Malta6, whereas the prevalence doubled in Sj6bo. The differences in fracture patterns between these two urban and rural communities may be explained by different lifestyles. Keywords: Fracture prevalence; Residence; Life-style
Introduction A difference in the incidence of hip fractures between rural and urban populations has been observed [1-3]. In the city of Malm6 the incidence of hip fractures was significantly higher than in the nearby rural municipalities, including Sj6bo [4]. Differences in bone mass in favour of this rural population have been described [5]. The aim of this study was to compare further the Correspondence and offprint requests to: Dr Brynj61fur Jdnsson, Department of Orthopaedics, Malta6 General Hospital, S-214 01 Malm6, Sweden.
fracture prevalence of all fragility fractures in the two communities.
Materials and Methods A comparative cross-sectional population-based study was carried out in Malta6 and Sj6bo. Malta6, in the south of Sweden, is the third largest city in the country a centre of industry and trade with 236000 residents. Sj6bo, a municipality 60 km east of Malta6, is one of the most typical agricultural communities in Sweden. It has 15000 residents. Some differences in demographic characteristics of the two communities are shown in Table 1. Included in the study were men and women of Scandinavian ethnic background born in 1908, 1918, 1928 and 1938, and women born in 1948. The probands in Sj6bo were all randomly selected from the National Population Records. In Malm6 sex- and age-matched controls were selected from the city files on population. The size of the urban group (women) was deliberately made larger because of a planned intervention study. The recruitment was identical for both populations. A letter with information on the purpose and methods of the study was followed by a telephone call. The probands were asked to answer questions about medical and social background and previous fractures. The fracture histories of the Malm6 probands were confirmed in the Department of Diagnostic Radiology at Malm6 Hospital, where all films and files have been saved since the turn of the century. Also, files in the
B, Jdnsson et al.
270
Table 1. Some demographic characteristics of Maim6 and SjObo Sweden Persons gainfully employed in agriculture and forestry (%) Persons receiving social benefits, 1987 (%)
Men living alone, 1985 (%) Women living alone, 1985 (%) Number of persons per 100 households, t985
Living in one-family homes, 1985 (%) Employment density, aged 60-64 (%) Men Women Age 65 years and over (%) Households of retired pensioners, 1985 (%)
Maim6
Sj6bo
Results In Sj6bo of 486 individuals invited to participate in the study, 391 (80%) did so. Of the 782 invited in Malm6, 570 participated (73%) (Table 2). Because of documentation in the archives, information on fractures in nonresponders also was available.
5
1
18
6 16 20
13 20 27
6 15 15
2.23 46
1.88 17
2.40 84
--18
59.8 46.5 21
70.9 45.8 20
40 years 50 years
23
26
26
60 years
17
10
70 yea~
7.6 32.5
5.5 25.9
Old age pensioners receiving social domestic help, I987 (%) 18 Pensioners on early retirement per 1000 All adults aged 16-64, 1987 6,3 Upper age group 60-64, 1987 30.7
From Statistics Sweden 1989 (Central Bureau of Statistics, S-115 81 Stockholm, Sweden).
Department of Orthopaedics were checked. In Sj6bo the local patient records for the probands were screened for fracture episodes, as were the records of Ystad Hospital where fractures in the Sj6bo population are treated. For each fracture, where possible, the degree of trauma as well as the age at the time of the fracture was noted. A fall from standing height was considered lowenergy trauma. Some of the most common fractures in elderly women have been associated with bone fragility. Therefore fractures of the distal end of the radius, the proximal end of the humerus, hip, vertebrae, rami of the pelvis and of the tibial condyles were grouped together and classified as fragility fractures [6]. The entire group was divided into responders and nonresponders. For responders, the urban (Malta6) and rural (Sj6bo) groups were each subdivided into two subgroups. One subgroup consisted of individuals who were raised and still living in the city at the time of the study - true urban (TU). Another consisted of individuals raised and still living in the countryside - true rural (TR). Bone mineral content (BMC) of both forearms was measured using single photon absorptiometry (SPA) at 1 and 6 cm proximal to the tip of the styloid process of the ulna [7].
Table 2. Participation rates of urban and rural probands Age group
Sex
Participation rate (%)
F M F M F M F M F M F
80 years
Total Toml
Urban
Rural
76 73 77 83 73 80 71 77 51 79 69
93 76 90 87 85 85 85 67 56 80 81
73
80
There was no significant difference in the prevalence of fractures sustained after the age of 30 between responders and non-responders in the rural group, the figure being 16% in both. Among urban dwellers there was a significantly higher prevalence of fractures in the non-responders compared with the responders: 35% compared with 26% (p
Osteoporosis International
Original Article Differences in Fracture Pattern Between an Urban and a Rural Population: A Comparative Population-Based Study in Southern Sweden B. J6nsson 1, P. Gfirdsell 1, O. Johnell I, I. Redlund-Johnell 2 and I. Sernbo ~ Departments of ~Orthopaedics and ZDiagnostic Radiology, Maim6 General Hospital, Malm6, Sweden
Abstract. Differences in the incidence of hip fractures have been reported between urban and rural areas. In this population-based study the characteristics of fracture patterns between the city of Malta6 and the nearby rural district of Sj6bo were compared. A total of 782 individuals in Malta6 and 486 in Sj6bo were invited to participate. Fracture history for all invited was registered. The odds ratio for fracture was higher in Malm6, particularly for women over 70. More than half of the urban women aged 70 had a history of a fracture. A fourfold increase in fracture prevalence between the ages of 60 and 70 was observed in women in Malta6, whereas the prevalence doubled in Sj6bo. The differences in fracture patterns between these two urban and rural communities may be explained by different lifestyles. Keywords: Fracture prevalence; Residence; Life-style
Introduction A difference in the incidence of hip fractures between rural and urban populations has been observed [1-3]. In the city of Malm6 the incidence of hip fractures was significantly higher than in the nearby rural municipalities, including Sj6bo [4]. Differences in bone mass in favour of this rural population have been described [5]. The aim of this study was to compare further the Correspondence and offprint requests to: Dr Brynj61fur Jdnsson, Department of Orthopaedics, Malta6 General Hospital, S-214 01 Malm6, Sweden.
fracture prevalence of all fragility fractures in the two communities.
Materials and Methods A comparative cross-sectional population-based study was carried out in Malta6 and Sj6bo. Malta6, in the south of Sweden, is the third largest city in the country a centre of industry and trade with 236000 residents. Sj6bo, a municipality 60 km east of Malta6, is one of the most typical agricultural communities in Sweden. It has 15000 residents. Some differences in demographic characteristics of the two communities are shown in Table 1. Included in the study were men and women of Scandinavian ethnic background born in 1908, 1918, 1928 and 1938, and women born in 1948. The probands in Sj6bo were all randomly selected from the National Population Records. In Malm6 sex- and age-matched controls were selected from the city files on population. The size of the urban group (women) was deliberately made larger because of a planned intervention study. The recruitment was identical for both populations. A letter with information on the purpose and methods of the study was followed by a telephone call. The probands were asked to answer questions about medical and social background and previous fractures. The fracture histories of the Malm6 probands were confirmed in the Department of Diagnostic Radiology at Malm6 Hospital, where all films and files have been saved since the turn of the century. Also, files in the
B, Jdnsson et al.
270
Table 1. Some demographic characteristics of Maim6 and SjObo Sweden Persons gainfully employed in agriculture and forestry (%) Persons receiving social benefits, 1987 (%)
Men living alone, 1985 (%) Women living alone, 1985 (%) Number of persons per 100 households, t985
Living in one-family homes, 1985 (%) Employment density, aged 60-64 (%) Men Women Age 65 years and over (%) Households of retired pensioners, 1985 (%)
Maim6
Sj6bo
Results In Sj6bo of 486 individuals invited to participate in the study, 391 (80%) did so. Of the 782 invited in Malm6, 570 participated (73%) (Table 2). Because of documentation in the archives, information on fractures in nonresponders also was available.
5
1
18
6 16 20
13 20 27
6 15 15
2.23 46
1.88 17
2.40 84
--18
59.8 46.5 21
70.9 45.8 20
40 years 50 years
23
26
26
60 years
17
10
70 yea~
7.6 32.5
5.5 25.9
Old age pensioners receiving social domestic help, I987 (%) 18 Pensioners on early retirement per 1000 All adults aged 16-64, 1987 6,3 Upper age group 60-64, 1987 30.7
From Statistics Sweden 1989 (Central Bureau of Statistics, S-115 81 Stockholm, Sweden).
Department of Orthopaedics were checked. In Sj6bo the local patient records for the probands were screened for fracture episodes, as were the records of Ystad Hospital where fractures in the Sj6bo population are treated. For each fracture, where possible, the degree of trauma as well as the age at the time of the fracture was noted. A fall from standing height was considered lowenergy trauma. Some of the most common fractures in elderly women have been associated with bone fragility. Therefore fractures of the distal end of the radius, the proximal end of the humerus, hip, vertebrae, rami of the pelvis and of the tibial condyles were grouped together and classified as fragility fractures [6]. The entire group was divided into responders and nonresponders. For responders, the urban (Malta6) and rural (Sj6bo) groups were each subdivided into two subgroups. One subgroup consisted of individuals who were raised and still living in the city at the time of the study - true urban (TU). Another consisted of individuals raised and still living in the countryside - true rural (TR). Bone mineral content (BMC) of both forearms was measured using single photon absorptiometry (SPA) at 1 and 6 cm proximal to the tip of the styloid process of the ulna [7].
Table 2. Participation rates of urban and rural probands Age group
Sex
Participation rate (%)
F M F M F M F M F M F
80 years
Total Toml
Urban
Rural
76 73 77 83 73 80 71 77 51 79 69
93 76 90 87 85 85 85 67 56 80 81
73
80
There was no significant difference in the prevalence of fractures sustained after the age of 30 between responders and non-responders in the rural group, the figure being 16% in both. Among urban dwellers there was a significantly higher prevalence of fractures in the non-responders compared with the responders: 35% compared with 26% (p
