ARC Epidemiology Unit, University of Manchester, Manchester,
1 Pain Relief and Rheumatology, Royal Bolton Hospital, Minerva Road, Bolton,
2 Rheumatology Department, Royal Lancaster Infirmary, Ashton Road, Lancaster,
3 Royal Oldham Hospital, Rochdale Road, Oldham,
4 Rheumatology Department, Macclesfield District General Hospital, Victoria Road, Macclesfield,
5 Rheumatology Department, Withington Hospital, Nell Lane, Manchester,
6 General Medicine, Manchester Royal Infirmary, Oxford Road, Manchester,
7 Rheumatology Department, Blackpool Victoria Hospital, Whinney Heys Road, Blackpool and
8 Rheumatology Department, Wrightington Hospital, Hall Lane, Wrightington, Lancashire, UK
SIR, Osteoporosis may be classified as either primary or secondary depending on whether or not there is a known underlying cause. Previous studies have suggested that in men secondary causes are common (>50%). However, most studies have been undertaken in single centres with an interest in metabolic bone disease, and it is possible that referral bias may explain in part the high prevalence of secondary causes [17]. The aim of our study was to determine the relative proportions of vertebral fractures due to primary and secondary osteoporosis in men across a range of clinical settings, including teaching and district general hospitals. We also looked at the underlying secondary causes of osteoporosis.
A descriptive survey method was used. The setting was medical (predominantly rheumatology) out-patient clinics in nine hospitals in the north-west of England. These included teaching [3] and district general hospitals [6]. Consecutive men attending these clinics with radiographically confirmed vertebral fractures were included in the survey. For each patient, the clinician characterized what they considered to be the main cause of the fracture (osteoporosis/trauma/other). Fractures due to osteoporosis were categorized as being due to either primary or secondary osteoporosis. If the fracture was due to secondary osteoporosis, the underlying cause(s) of the osteoporosis was recorded.
One hundred and fifty-nine men with vertebral fracture (mean age 60.8 yr, S.D.=13.5 yr) were included in the survey. In 154 men the fracture was considered to be due to osteoporosis. In the other five the fracture was due to trauma (two), malignancy (two) and Paget's disease (one). Of the 154 cases of osteoporosis, 81 (53%) were considered to be due to primary or idiopathic osteoporosis and 73 (47%) to have an underlying secondary cause. There was no difference in the proportion of patients with secondary causes identified in teaching hospital centres (43%) and in the district general hospitals (55%) (2=2.25, P=0.13). The most frequent secondary causes were corticosteroids [34 (47%)], alcohol excess [10 (14%)] and hypogonadism [7 (10%)]. Eight (11%) patients had various other causes while in 14 (19%) there was more than one underlying cause. The mean age of those with primary osteoporosis was similar to that of those with secondary osteoporosis (61.5 vs 59.3 yr).
A recent pooled analysis of several studies suggests that 58% of men have an underlying secondary cause of osteoporosis [17]. In a more recent study in the UK, Evans et al. [8] found that 52% of a group of 220 men had a secondary cause. In our study, the frequency of secondary causes was similar (47%). Furthermore, there was no important difference in the relative proportions of primary and secondary causes in those attending teaching hospital centres and those in the district general hospitals, which provides some reassurance that in this study referral bias does not explain the findings. Our data confirm observations in previous studies that the most frequent underlying secondary causes of osteoporosis are alcohol excess, corticosteroid therapy and hypogonadism [7, 8]. In summary, in men attending hospital clinics with osteoporotic vertebral fracture in the north-west of England, approximately 50% will have an underlying secondary cause of osteoporosis.
Notes
Correspondence to: T. W. O'Neill. E-mail: terry{at}fs1.ser.man.ac.uk
References