Osteoporos Int (1999) 9:129–133 ß 1999 International Osteoporosis Foundation and National Osteoporosis Foundation
Osteoporosis International
Original Article Usefulness of Armspan and Height Comparison in Detecting Vertebral Deformities in Women R. G. J. A. Versluis1, H. Petri1, C. M. van de Ven2, A. B. J. Scholtes3, E. R. Broerse1, M. P. Springer1 and S. E. Papapoulos4 1 Department of General Practice, Leiden University Medical Centre, Leiden; 2Merck Sharp & Dohme, Haarlem; 3General Practice ‘Wantveld’, Noordwijk; and 4Clinical Investigation Unit of the Department of Endocrinology and Metabolic Diseases, Leiden University Medical Centre, Leiden, The Netherlands
Abstract. The prevalence of vertebral fractures in women increases with age but only about one third of these fractures are symptomatic. On the other hand, the presence of vertebral fractures is an independent risk factor for new osteoporotic fractures. In the present study we examined the hypothesis that differences between armspan and height are related to the presence of vertebral deformities in a cohort of 494 women aged between 55 and 84 years (mean age 67.6 years, SD 8.2 years) who were randomly selected from a large general practice in The Netherlands. Height and armspan were measured and vertebral morphometry of lateral radiographs of the spine was performed. Both height and armspan decreased significantly with age. The correlation between armspan and height was 0.83. Vertebral deformities were present in 32.7% of the women (grade I in 22.4% and grade II in 10.3%). Only the prevalence of grade II deformities rose with age. The variation of the difference between armspan and height in the groups with or without grade II vertebral deformities was comparable and relatively large (range >15 cm). The difference in mean values was small between those groups (1.6 cm) and could not differentiate between women with and without vertebral deformities. Our data show that the presence of vertebral deformities cannot be detected by the difference between armspan and height. Keywords: Armspan; Height; Osteoporosis; Vertebral deformities Correspondence and offprint requests to: R. G. J. A. Versluis, MD, Department of General Practice, Leiden University Medical Centre, PO Box 2088, 2301CB Leiden, The Netherlands. Tel: +31 71 5275318. Fax: +31 71 5275325.
Introduction In recent years there have been major advances in diagnosing and treating postmenopausal osteoporosis. However, the problem of selecting the women who will most likely benefit from these advances has not been solved and case-finding strategies based mainly on clinical risk factors are currently recommended [1]. The prevalence of vertebral fractures increases with age in women but only one third of these fractures give rise to symptoms [2,3]. On the other hand, it has been demonstrated that the presence of vertebral fractures is an independent risk factor for new osteoporotic fractures [2,4]. Identification of these asymptomatic individuals may therefore help in the design of case-finding strategies and eventually in reducing the risk of osteoporotic fractures. For this a simple, sensitive and convenient screening method for general practice is needed. As early as the first century AD the Roman architect Vitruvius noted the relation between armspan and height, which was later elegantly depicted by Leonardo da Vinci in his famous drawings of the ‘Diagram of Man’ [5,6]. More recently Harris et al. [7] showed the equality of armspan and height in anthropometric studies of young adults. As height, but not armspan, is affected by vertebral fractures it was suggested that these measurements may be helpful in identifying osteoporotic individuals [5,8–13]. Indeed Nores et al. [14], in a small group of hospitalized patients, reported that a difference between armspan and height of 5 cm or more was highly predictive of vertebral fractures. In the present study we examined the hypothesis that differences between
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R. G. J. A. Versluis et al.
armspan and height are related to the presence of vertebral deformities in a cohort of women aged between 55 and 84 years.
performed 3 times, or 5 times when individual measurements differed by 5 mm or more. The mean was used for the analysis.
Subjects and Methods
Intra- and Inter-observer Variation of Height and Armspan Measurement
The study was performed in a large general practice in Noordwijk, The Netherlands, and was part of a study examining risk factors for osteoporosis in elderly women. Within the Dutch health care system nearly every individual is registered in a general practice regardless of medical condition. At the time of the study 1325 women aged between 55 and 84 years were registered in the general practice concerned. These were stratified in 5-year age groups and a cohort of 771 women was randomly selected for the study. Of these 44 were excluded because they were bedridden (n = 4), wheelchair-bound (n = 11), incompetent to participate (n = 12) or had a concurrent serious illness (n = 17). An additional 8 women had moved away and 7 had died at the time of selection. The remaining 712 women were invited by mail to participate in the study, a questionnaire being enclosed with the invitation. If there was no response, a reminder was sent after 3 weeks. In total 494 (69%) women (mean age 67.6 years, SD 8.2 years) responded to the invitation and attended the clinic. At this stage 45 women were excluded from the study for the following reasons: no informed consent for radiographs (n = 17), no suitable hip for dual-energy X-ray absorptiometry (n = 10), inability to measure height or armspan (n = 15), non-Caucasian (n = 3). Thus height and armspan measurements and spinal radiographs were finally performed in 449 women. All women gave informed consent and the study was approved by the Medical Ethics Committee of the Leiden University Medical Centre.
Anthropometric Measurements Height was measured by a stadiometer with an accuracy of 1 mm. The subject was positioned, without shoes, with heels, buttocks and back to the upright board. The head was positioned in the Frankfort horizontal plane (a horizontal plane represented in profile by a line between the lowest point on the margin of the orbit and the highest point on the margin of the acoustic (auditory) meatus) and the headplate brought into firm contact with the vertex [15]. Armspan was measured with a calibrated horizontal stadiometer (accurate to 1 mm) which was movable in the vertical plane. This had two plates, one fixed and one sliding, and was placed at the level of the shoulder. With the subject standing with the arms fully extended and palms facing forward, the distance between the tips of the middle fingers was measured. In 15 subjects armspan could not be measured as a result of a disease of the shoulder and/or elbow. Height and armspan were measured by two observers and each subject by one. Each measurement was
The intra- and inter-observer variation in height and armspan measurements was assessed in 20 women by the two observers, using the methods of Bland and Altman [16]. The intra-observer mean differences of height and armspan measurements were 0.1 mm (95% CI: –2.3 to 2.5 mm) and 0.9 mm (95% CI: –2.5 to 4.3 mm), respectively, and the 95% limits of agreement were –10.3 to 10.5 mm and –13.5 to 14.4 mm. The inter-observer mean differences of height and armspan measurements were –1.6 mm (95% CI: –3.2 to 0.1 mm) and –4.6 mm (95% CI: –7.7 to –1.5 mm), respectively, and the 95% limits of agreement were –8.8 to 5.7 mm and –17.9 to 8.7 mm.
X-ray Morphometry Lateral radiographs of the spine including T4 and L5 were made and vertebral morphometry was assessed using the method of Eastell et al. [17]. Twenty-one radiographs (4.7%) were unreliable for analysis for technical reasons. The degree of deformity of each vertebra was assessed by measurement of anterior height (AH), central height (CH) and posterior height (PH) of T4 to L4 using a cross-wired cursor and an illuminated digitizing board. The following ratios were calculated: AH/PH, CH/PH, PH/PHupper adjacent vertebra, PH/PHlower adjacent vertebra. Deviation of any one of these ratios below a given cut-off level indicates vertebral deformity. A deviation of between –3 and –4 standard deviations (SD), or of below –4 SD, was recorded as a grade I (moderate) or grade II (severe) deformity, respectively [17]. The morphometric analysis was done by the same technicians who analyzed a large population study in Rotterdam, using the same equipment and reference values [18].
Statistics The relationship between age and height or armspan was calculated by linear regression. Pearson correlation coefficient was computed for the relationship between armspan and height. The means of the differences between armspan and height for the different groups of vertebral deformities were compared by independent t-tests using the statistical program SPSS.
Results Height declined with age (Fig. 1, upper panel). Armspan also declined with age, though the decrease was about
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Fig. 2. Relationship between height and armspan in 428 women (r = 0.83, p < 0.001).
Fig. 1. Upper panel: relationship between age and height in 428 women; the decline in height was 0.23 cm/year, (p <0.001). Lower panel: relationship between age and armspan in the same group of women; the decline in armspan was 0.14 cm/year (p <0.001).
half that of the decline in height: 0.14 cm/year versus 0.23 cm/year (Fig. 1, lower panel). There was a highly significant correlation between armspan and height (r = 0.83, p <0.001; Fig. 2). The mean difference between armspan and height was 1.4 cm in women aged between 55 and 59 years and rose to 3.2 cm in those aged between 80 and 84 years. Grade II vertebral deformities increased with age from 3.4% in women aged between 55 and 59 years to 21.9% in those aged between 80 and 84 years (Table 1). In contrast, the frequency of grade I deformities did not change with age (Table 1). There were differences between armspan and height of more than 10 cm, which were equally distributed among women with no vertebral deformities, grade I deformities and grade II deformities. There was a substantial overlap of the values for the different groups (Fig. 3). No statistically significant difference
Table 1. Height, armspan, difference between armspan and height and the prevalence of vertebral deformities in women aged 55–84 years Age (years)
n
55–59 60-64 65-69 70-74 75-80 80-84
87 93 82 69 56 41
Total
428
a
Heighta (cm)
c
Armspan-height (cm)
Vertebral deformities Grade I
Grade II
Mean
(SD)
Mean
(SD)
Mean (SD)
%
(n)
%
(n)
164.9 164.7 163.6 161.1 160.9 159.7
(5.6) (5.5) (5.6) (5.4) (5.6) (6.1)
166.4 167.0 165.8 164.6 164.4 163.0
(7.2) (6.1) (5.9) (6.5) (6.6) (6.6)
1.4 2.4 2.2 3.5 3.5 3.2
(4.0) (3.1) (3.4) (4.4) (4.8) (3.9)
25.3 19.4 22.0 20.3 23.2 26.8
(22) (18) (18) (14) (13) (11)
3.4 6.5 8.5 14.5 16.1 21.9
(3) (6) (7) (10) (9) (9)
165.6 (6.6)
2.5
(3.9)
22.4
(96)c
10.3
(44)d
163.0 (5.9)
Decline 0.23 cm/year (p <0.001). Decline 0.14 cm/year (p <0.001). 78% solitary (n = 75). d 66% solitary (n = 29). b
Armspanb (cm)
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R. G. J. A. Versluis et al. Table 2. Characteristics of the difference between armspan and height, for several cut-off levels, for the presence of grade II vertebral deformities Cut-off level of the difference between armspan and height
Sensitivity Specificity Positive predictive value
5.0 cm
7.0 cm
9.0 cm
0.39 (17/44) 0.76 (292/384) 0.16 (17/109)
0.18 (8/44) 0.89 (343/384) 0.16 (8/49)
0.11 (5/44) 0.95 (366/384) 0.22 (5/23)
Fig. 3. Boxplots of the difference between armspan and height for the groups with no vertebral deformities (n = 288; mean 2.6 cm, SD 4.0 cm), grade I verebral deformities (n = 96; mean 1.9 cm, SD 3.6 cm) and grade II vertebral deformities (n = 44; mean 4.0 cm, SD 4.2 cm).
in means of the difference between armspan and height among the groups with or without any vertebral deformity were found. When the results of the groups with or without grade I vertebral deformities were pooled and compared with those of the women with grade II deformities, there was a statistically significant difference in means of 1.6 cm (p <0.05). As a result of the large range of measurements and overlap the sensitivity and positive predictive value of the measurement were low (Table 2). For example sensitivity, specificity and positive predictive value at a cut-off level of 7.0 cm were 0.18, 0.89 and 0.16, respectively.
Discussion Vertebral deformities are common in elderly women and are associated with a higher risk for future fractures [2,4]. Although they are related to age and are associated with loss of height, disability and pain, the majority are asymptomatic [2,10,19]. Unfortunately there is no simple and useful method to detect the presence of vertebral fractures [20]. In the present study we examined the usefulness of the difference between armspan and height in detecting vertebral deformities
in a cohort of women aged between 55 and 84 years, representative of the general population. A statistically significant difference in means between armspan and height of 1.6 cm was found when women with grade II vertebral deformities were compared with the rest. However, the measurements in the different groups with vertebral deformities was large and the overlap substantial. Therefore, the difference between armspan and height cannot predict the presence of any vertebral deformity (either grade I or grade II). There is a large variation in the prevalence of vertebral deformities in European women [21]. Even within one country large differences have been reported. There are several difficulties in comparing prevalences of vertebral deformities because of the different morphometric methods and reference values used. Because of differences in age-distributions, comparison between countries and studies is difficult. When we compare the prevalence of vertebral deformities of our study with that of the European Vertebral Osteoporosis Study we have a very high rate of deformities [21]. However, when we compare it with another Dutch population study, namely the Rotterdam study, in which the same reference values were used, the prevalence of the grade II deformities was very similar for all age groups [18]. The prevalence of grade I deformities in our study was, however, higher. It should be mentioned that the relevance of grade I deformities is questionable as these are not related to pain, disability or loss of height [10,19]. Apart from vertebral deformities other factors may contribute to variations in armspan–height differences. These include biologic and observer variables. Of the former, disk degeneration may lead to decreases in height. Although older women with more vertebral deformities and presumably more degenerative changes of the spine showed higher mean differences between armspan and height than younger women, the measurement could not identify those with vertebral deformities in the latter group even if considered separately. Other sources of variation are racial differences and concurrent disease of the shoulder or elbow [5]. As only Caucasian women were studied, and the women with diseases of the elbow and shoulder were excluded from the analysis, these factors did not contribute to our results. Finally the intra- and inter-observer variations were small and it is unlikely that these contributed significantly to the observed large variations and substantial overlap in measurements.
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Only one study has reported a substantial difference between armspan and height for the groups with or without vertebral fractures [14]. In that study, however, a hospitalized population was used, and height was not measured directly but taken from identity papers. The spread of the differences between armspan and height in our cohort was large; thus we do not think that the positive predictive value of the measurement will improve much in a more selected population. We therefore conclude that the comparison of armspan and height is not a useful instrument to predict the presence of vertebral deformities in women of 55 years and older.
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Acknowledgements. We would like to thank all general practitioners of primary health care centre ‘Wantveld’ for their help in this study, and Mrs W. van der Giessen-de Jager for technical assistance. The study was partly supported by a grant from Merck Sharp & Dohme, The Netherlands.
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Received for publication 24 December 1997 Accepted in revised form 20 May 1998
