Osteoporosis is a systemic skeletal disorder characterized by decreased bone strength and deterioration of bone microarchitecture, resulting in increased susceptibility to fragility fractures [1,2]. Because bone loss progresses without early clinical manifestations, the condition is often undetected until a fracture occurs, making it a major public health concern worldwide [3]. Globally, osteoporosis affects millions of individuals and is associated with significant morbidity, mortality, and economic burden [3,4]. Although the disease occurs in both sexes, women are disproportionately affected, particularly after menopause. Estrogen deficiency plays a central role in accelerating bone resorption and disrupting the balance of bone remodeling, leading to rapid bone mineral density decline during the postmenopausal period [6,7]. As a result, postmenopausal women represent the highest-risk group for osteoporosis and osteoporotic fractures [7]. Age is another major determinant of bone loss. Peak bone mass is typically achieved during early adulthood, after which a gradual decline   begins. This   decline becomes more pronounced  with advancing age, especially beyond the fifth decade of life [2,4]. International data indicate that fracture incidence increases exponentially with age, particularly among women over 50 years [3,4]. Although osteoporosis is more frequently diagnosed in women, men are also affected. Age-related bone loss in males occurs more gradually but remains clinically significant, particularly in older age groups [7,8]. However, osteoporosis in men is often underdiagnosed and undertreated despite measurable morbidity and mortality risks [5]. Body mass index (BMI) has also been implicated in bone health. While increased body weight has traditionally been considered protective due to mechanical loading effects on bone, emerging evidence suggests that obesity does not necessarily improve bone quality and may contribute to altered bone metabolism [5,8]. Therefore, the relationship between BMI and osteoporosis remains complex and may vary across populations. Due to the increasing osteoporosis prevalence with age, the worldwide aging of the population and the changing lifestyle habits, the prevalence of osteoporosis has risen significantly and will continue to in the future [9]. As a result, there will also be an increase in both the prevalence and incidence of related fragility fractures. In 1990 it was projected that by 2050, the worldwide incidence of hip fracture in men would increase by 310% and 240% in women [10]. In 2010, there were an estimated 158 million individuals at high fracture risk, by 2040 it was estimated that this figure will double because of demographic shifts [11]. In Iraq, limited epidemiological data exist regarding osteoporosis prevalence and associated risk factors. Studies conducted among Iraqi and regional populations have reported a high prevalence of osteoporosis among postmenopausal women, with age and hormonal status being key determinants [10-12]. However, comparative data between women and men in Kirkuk city remain scarce. Therefore, the present study aims to evaluate the distribution of osteoporosis according to age, sex, and BMI among patients in Kirkuk city, Iraq, with particular emphasis on postmenopausal women, and to compare the findings with regional and international studies.

Patients and Methods

A hospital-based cross-sectional study was conducted at two major hospitals in Kirkuk City, Iraq, among patients undergoing assessment of bone mineral density (BMD). The study included participants of both sexes aged 10–100 years who attended the participating hospitals during the study period. A total of 5,696 eligible participants were included in the final analysis.

Study Population and Eligibility Criteria

Patients were considered eligible if they were aged 10–100 years, underwent BMD assessment using dual-energy X-ray absorptiometry (DXA), and had sufficient demographic, anthropometric, and clinical information for analysis.

        Patients with chronic diseases known to substantially affect bone metabolism were excluded. Individuals with osteomalacia or recognized secondary causes of osteopenia or osteoporosis were also excluded to minimize potential confounding from conditions associated with secondary bone loss.

Data Collection and Clinical Assessment

Data were collected using a standardized clinical assessment. Demographic and clinical variables included age, sex, anthropometric measurements, and history of osteoporotic fracture. Height and body weight were measured, and body mass index (BMI) was calculated as weight in kilograms divided by the square of height in meters (kg/m²). For the principal analyses, age was categorized into ≤45 and >45 years to evaluate age-related differences in BMD status. BMI was categorized as ≤25 and >25 kg/m² according to the predefined analytical classification used in the study. Among women, particular attention was given to participants aged >45 years because this group represented the older female population in whom age- and menopause-related bone loss was expected to be more prominent. However, age >45 years should not itself be considered equivalent to confirmed postmenopausal status unless menopausal status was directly recorded.

Bone Mineral Density Measurement

BMD was measured using dual-energy X-ray absorptiometry (DXA) at two clinically relevant skeletal sites: the lumbar spine and femoral neck. Measurements were obtained according to the operating procedures of the DXA system and expressed as T-scores. For each participant, bone status was determined according to the lowest relevant T-score obtained at the lumbar spine or femoral neck.

Definition of Bone Mineral Density Categories

Bone status was classified according to the World Health Organization (WHO) T-score criteria [13]. Osteoporosis was defined as a T-score ≤−2.5 at either the lumbar spine or femoral neck. Among participants who did not meet the criterion for osteoporosis, osteopenia (low bone mass) was defined as a T-score between −1.0 and −2.5. A T-score ≥−1.0 was categorized as normal BMD. For calculation of lumbar spine T-scores, the reference database supplied by the DXA manufacturer was used. In the absence of an internationally standardized lumbar spine reference population, the reference values were based on BMD measurements from 30-year-old White women, consistent with the reference approach specified for the DXA system [14,15].

Assessment of Osteoporotic Fracture History

A history of osteoporotic fracture was recorded during clinical assessment and categorized as present or absent. Fracture history was evaluated in relation to BMD category and sex to investigate differences in fracture distribution across the study population.

Study Variables and Outcomes

The primary outcome was BMD status, classified as normal BMD, osteopenia, or osteoporosis. The principal explanatory variables were age, sex, and BMI. History of osteoporotic fracture was additionally evaluated as an important clinical variable. The analyses therefore examined: (1) BMD status according to age group among females; (2) BMD status according to age group among males; (3) the association between BMI category and BMD status; (4) the relationship between osteoporotic fracture history and BMD status; and (5) the distribution of osteoporotic fractures according to sex.

Statistical Analysis

Data were analyzed using SPSS ver 26. Continuous variables were summarized as mean±standard deviation (SD), whereas categorical variables were presented as frequencies and percentages, as appropriate. Associations between categorical variables, including age group, sex, BMI category, fracture history, and BMD status, were evaluated using the chi-square test or Fisher's exact test, as appropriate. All statistical tests were two-sided, and a P value<0.05 was considered statistically significant.

Ethical Considerations

The study was conducted in accordance with the ethical principles of the Declaration of Helsinki. Participant confidentiality was maintained throughout data collection, analysis, and reporting, and data were used exclusively for research purposes.

A total of 5,696 participants were included in the study. Females constituted the majority of the sample (5,164; 90.66%), while males represented 532 participants (9.34%) as in Figure 1.

Figure 1: Sex Distribution of Studied Patients

Among females aged ≤45 years (mean age 34.70±4.04 years), the distribution was as follows, those have normal BMD: 307 (5.94%), Osteopenia: 268 (5.18%) and Osteoporosis: 145 (2.80%). No statistically significant association was observed in this age group (p = 0.069). In females aged >45 years (mean age 63.01±2.15 years): those have Normal BMD: 1,176 (22.77%), Osteopenia: 1,789 (34.64%) and Osteoporosis: 1,479 (28.64%). A statistically significant association between age >45 years and reduced bone mineral density was observed (p = 0.013) as in Figure 2.

Figure 2: Age Distribution and Bone Status in Females

Among males aged ≤45 years (mean age 31.15±2.78 years): those have Normal BMD: 41 (7.60%), Osteopenia: 56 (10.46%) and  Osteoporosis: 36 (6.72%). No significant association was found in this age group (p = 0.069). In males aged >45 years (mean age 64.71±5.65 years the result was as follow those with  Normal BMD: 125 (23.36%), Osteopenia: 179 (33.46%) and Osteoporosis: 98 (18.40%) A statistically significant association was observed (p = 0.049) as in Figure 3.

Figure 3: Age Distribution and Bone Status in Males

 Among participants with BMI ≤25: THOSE Normal DXA RESULT WAS: 282 (4.95%), Osteopenia: 536 (9.41%)  and Osteoporosis: 650 (11.40%) ,No statistically significant association was found (p = 0.0872). Among participants with BMI >25: those with Normal DXA result was: 1,366 (23.98%), Osteopenia: 1,757 (30.84%) and  Osteoporosis: 1,108 (19.45%). A statistically significant association between BMI >25 and bone mineral density was observed (p = 0.0137) as in Figure 4 (Table 1).

Table 1:  Association of Age, Sex, and BMI with Bone Mineral Density Status

Figure 4: Body Mass Index (BMI) and Bone Status

Among participants with a history of osteoporotic fracture: those with Normal DXA result was: 102 (1.79%), Osteopenia: 300 (5.26%) and Osteoporosis: 363 (6.30%), No statistically significant difference was observed (p = 0.0861). Among participants without fracture: those with Normal DXA result was: 1,546 (27.18%), Osteopenia: 1,993 (34.98%) and Osteoporosis: 1,395 (24.49%). A statistically significant association was identified (p = 0.0269) as in Figure 5.

Figure 5:   Osteoporotic Fracture and Bone Status

Among males: those who have Osteoporotic fracture:  No. was 62 (1.08%) and those with no fracture: 470 (8.25%). p = 0.0026. Among females:  those who have Osteoporotic fracture: 703 (12.36%) and those with no fracture: 4,461 (78.31%). p = 0.0001 Both male and female groups showed statistically significant differences in fracture distribution (Table 2, Figure 6).

Table 2: Association of Osteoporotic Fracture History and Sex with Bone Status

Figure 6: Sex and Osteoporotic Fracture

The findings of the present study demonstrate a marked predominance of osteoporosis among women in Kirkuk city, particularly after the age of 45 years. This gender-based difference is biologically plausible and consistent with the pathophysiology of postmenopausal bone loss. Estrogen plays a fundamental role in maintaining skeletal integrity by regulating bone remodeling. Its decline during menopause accelerates osteoclastic activity, resulting in progressive bone mineral density reduction [16,17].  Advancing age was identified as a statistically significant determinant of osteoporosis in both females and males. Bone mass typically reaches its peak in early adulthood and subsequently declines with aging. However, in women, this decline becomes more pronounced following menopause due to hormonal imbalance [18,19]. International epidemiological data confirm that fracture incidence increases substantially after the fifth decade of life, supporting our findings [20,21]. Although osteoporosis is more frequently reported in women, our results indicate that men over 45 years also experience significant bone density reduction. Age-related bone loss in men occurs more gradually but remains clinically relevant. Previous research suggests that lower screening rates among men may contribute to under diagnosis, despite measurable age-associated decline in bone mass [22,23]. The association observed between higher BMI (>25) and osteoporosis in this population warrants careful interpretation. While increased body weight has historically been considered protective due to mechanical loading, recent evidence indicates that adiposity may negatively influence bone quality through inflammatory mediators and altered hormonal pathways [19,23]. Therefore, excess body weight does not necessarily guarantee improved skeletal strength. Fracture prevalence was notably higher among women compared to men. This pattern aligns with global fracture statistics indicating that women represent the majority of osteoporotic fracture cases [20,24]. Reduced peak bone mass, accelerated postmenopausal bone turnover, and longer life expectancy may explain this observation [17]. Regional comparisons further support the validity of our findings. Studies conducted in Iraq and neighboring Middle Eastern countries have reported similar age- and menopause-related patterns of osteoporosis distribution [25,26,27]. These consistent observations suggest that demographic and hormonal factors play a dominant role in osteoporosis epidemiology across the region.  Overall, the present study emphasizes age and female sex as primary determinants of osteoporosis in Kirkuk city. These findings reinforce international recommendations advocating early bone mineral density assessment in women approaching menopause to reduce fracture risk and long-term disability [16,28].

The present study demonstrated that osteoporosis is a common health problem among adults attending the two major hospitals in Kirkuk City, Iraq. The condition was observed more frequently among women, particularly those aged over 45 years, highlighting the important role of age and menopausal status in bone loss. Advancing age was significantly associated with reduced bone mineral density in both sexes, although the prevalence remained higher among females. In addition, a considerable proportion of participants with osteoporosis had a history of fractures, emphasizing the clinical and public health burden of the disease. The findings underscore the need for increased awareness, early screening, and timely intervention, especially among middle-aged and older women who are at greater risk. Implementation of preventive strategies, including routine bone mineral density assessment, promotion of healthy lifestyle practices, adequate calcium and vitamin D intake, and patient education programs, may contribute to reducing osteoporosis-related complications and improving quality of life among the population of Kirkuk City.

Study Limitations

This study has several limitations. First, its cross-sectional design precludes causal inference between risk factors and osteoporosis. Second, participants were recruited from hospitals, which may limit generalizability to the broader community. Third, the marked predominance of female participants may have affected sex-based comparisons. Finally, important factors such as vitamin D status, smoking, dietary calcium intake, physical activity, and medication use were not assessed.

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