1. Background
Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia, which can lead to various complications affecting multiple organ systems (1). Among these complications, diabetic foot disease poses a significant challenge due to its potential for severe morbidity and disability (2). In cases where conservative treatments fail, below-knee amputations (BKAs) are often performed to prevent the spread of infection and improve patient outcomes (3). However, the impact of such surgical interventions on the health-related quality of life (HRQoL) of diabetic foot patients warrants further investigation. The HRQoL is a multidimensional concept that encompasses an individual's physical, psychological, and social well-being as it relates to their health condition (4). Moreover, depression and anxiety that may develop following BKA have been shown to substantially reduce HRQoL in diabetic foot patients (5). Understanding the HRQoL outcomes in diabetic foot patients post-amputation is crucial for healthcare providers to tailor effective interventions and support systems (6).
2. Objectives
This study assesses HRQoL in diabetic foot patients following BKA using the short form health survey (SF-36) and the Hospital Anxiety and Depression Scale (HADS), and examines how demographic factors — age, sex, education, financial status, and surgical site infection (SSI) history — relate to post-operative outcomes.
3. Methods
This descriptive cross-sectional study was conducted at Firoozgar Hospital in Tehran between 2022 and early 2023. A total of 112 eligible diabetic foot patients who had undergone BKA were consecutively included using convenience sampling. Given the limited number of eligible patients at our center and the absence of sufficient prior data for an a priori power calculation, all cases meeting the inclusion criteria were included. Inclusion criteria comprised adults with diabetic foot who had undergone BKA, while patients with cognitive impairments or severe comorbidities preventing participation were excluded.
Each participant completed two validated instruments: The SF-36, which measures various domains of HRQoL, and the HADS, which assesses psychological distress. Both instruments have demonstrated strong psychometric properties. The SF-36 shows good construct validity, content validity, and internal consistency (Cronbach’s alpha: 0.70 - 0.99 across subscales), while the HADS demonstrates adequate construct and criterion validity, with Cronbach’s alpha values of 0.70 for depression and 0.85 for anxiety subscales in the Iranian population (7, 8). The SF-36 measures eight domains of physical and mental health, while the HADS specifically evaluates anxiety and depression.
Patients with limited literacy or mobility were interviewed by trained staff, either in person or by phone. Demographic information — including age, sex, education level, financial status, and history of post-operative SSI — was collected from medical records and participant reports. Collected data were analyzed using SPSS software. Descriptive statistics, including means ± SD, frequencies, and percentages, were used to summarize the data, and inferential analyses, including t-tests, ANOVA, chi-square tests, and correlation analyses, were performed to examine associations between variables.
The study protocol received ethical approval from the Institutional Review Board of Firoozgar Hospital (IR.IUMS.FMD.REC.1400.617). Written informed consent was obtained from all participants.
4. Results
The study included a total of 112 below-knee amputated patients. The mean age of participants was 62.5 ± 11.1 years. The majority were male (78 individuals; 69.6%). Regarding educational attainment, 34 patients (30.4%) held a college degree, while 20 (17.9%) were illiterate. In terms of income, nearly half (49.1%) reported low income, and 6.3% reported high income. Most patients (79.5%) were not admitted due to post-operative SSI; only 20.5% had documented SSI following amputation.
4.1. Associations Between Sociodemographic Factors and Health-Related Quality of Life Outcomes
The HRQoL was assessed using the SF-36 and HADS instruments. Associations were examined with key sociodemographic variables, including age, sex, educational attainment, income level, and SSI status. Increasing age was strongly and negatively correlated with physical functioning (R = -0.72, P < 0.001), pain (R = -0.49, P < 0.001), and overall physical health scores (R = -0.62, P < 0.001), indicating reduced physical capacity in older participants. Mental health domains and psychological distress showed no significant age-related trends. Sex-based differences were nonsignificant across most domains. However, female participants reported lower scores in energy/fatigue (vitality, P = 0.048), general health (P ≈ 0.052), and role emotional (P = 0.200), suggesting reduced perceived vitality and emotional functioning.
Educational attainment, categorized from illiteracy to college-level education, showed positive associations with physical functioning, role limitations, emotional well-being, and general health (all P < 0.05). Higher education was also linked to lower anxiety and depression scores on the HADS. Income level, categorized as low, moderate, or high, had minimal influence on SF-36 domains. Nonetheless, patients with low income reported significantly higher anxiety scores (HADS-A: P = 0.042) than those with moderate or high income. Finally, SSI status was associated with lower scores in physical functioning and role physical domains, but these differences were not statistically significant. Detailed values are presented in Table 1.
| Domain/Subscale | PF | RP | RE | EF | EW | SF | Pain (P) | GH | Physical Health a | Mental Health a | HADS-Anxiety | HADS-Depression |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gender | ||||||||||||
| Female | 11.91 | 0 | 2.94 | 13.97 | 21.52 | 18.75 | 28.08 | 9.26 | 49.26 | 57.19 | 17.85 | 16.02 |
| Male | 11.98 | 3.52 | 6.83 | 17.30 | 21.89 | 20.19 | 28.39 | 10.57 | 54.48 | 66.23 | 16.66 | 14.78 |
| P-value | 0.964 | 0.052 | 0.200 | 0.048 b | 0.873 | 0.593 | 0.915 | 0.341 | 0.287 | 0.154 | 0.144 | 0.096 |
| Age | ||||||||||||
| R | -0.72 | -0.21 | -0.14 | -0.01 | 0.08 | -0.18 | -0.49 | -0.03 | -0.62 | -0.11 | - | - |
| P-value | 0.001 b | 0.024 | 0.146 | 0.952 | 0.401 | 0.063 | 0.001 b | 0.790 | 0.001 b | 0.233 | 0.591 | 0.225 |
| Education | ||||||||||||
| College | 17.20 | 5.15 | 7.84 | 15.29 | 17.41 | 21.69 | 33.52 | 10.14 | 66.02 | 62.24 | - | - |
| Others | 7.25 | 0 | 3.33 | 19.56 | 25.20 | 23.75 | 22.12 | 10.00 | 39.37 | 75.52 | - | - |
| P-value | P < 0.001 b | 0.100 | 0.327 | 0.203 | 0.007 b | 0.059 | 0.023 b | 0.897 | < 0.001 b | 0.069 | ↓ P < 0.05 | ↓ P < 0.05 |
| Income | ||||||||||||
| Low | 11.09 | 0.45 | 4.24 | 15.00 | 22.47 | 19.54 | 25.09 | 9.45 | 46.09 | 61.26 | 17.14 | 15.52 |
| Others | 13.57 | 7.14 | 7.33 | 17.85 | 26.28 | 20.00 | 31.80 | 12.14 | 61.42 | 68.54 | 16.71 | 14.14 |
| P-value | 0.509 | 0.042 b | 0.560 | 0.262 | 0.348 | 0.984 | 0.048 b | 0.463 | 0.010 b | 0.731 | 0.042 b | 0.511 |
| SSI | ||||||||||||
| Yes | 9.34 | 1.08 | 1.44 | 14.13 | 20.34 | 19.02 | 31.73 | 10.00 | 52.17 | 54.94 | 17.95 | 15.73 |
| No | 12.64 | 2.80 | 6.74 | 16.85 | 22.15 | 19.94 | 27.41 | 10.22 | 53.08 | 65.69 | 16.78 | 15.01 |
| P-value | 0.078 | 0.408 | 0.126 | 0.764 | 0.157 | 0.490 | 0.187 | 0.886 | 0.870 | 0.137 | 0.206 | 0.396 |
Abbreviations: SSI, surgical site infection; PF, physical functioning; RP, role physical; RE, role emotional; EF, energy/fatigue; EW, emotional well-being; SF, social functioning; GH, general health; HADS, Hospital Anxiety and Depression Scale.
a Composite scores derived from multiple subscales.
b Values indicate statistically significant associations (P < 0.05).
5. Discussion
This study evaluated HRQoL among diabetic foot patients following BKA, using the SF-36 and HADS instruments. It explored the influence of key sociodemographic variables — including age, sex, educational level, income, and post-operative SSI — on physical and mental health outcomes. Consistent with previous research, this study affirms the substantial negative impact of lower limb amputation on HRQoL in diabetic populations. Prior studies by Ribu et al., Gershater et al., and Jeffcoate et al. documented significantly lower SF-36 scores among amputees, particularly in domains related to physical functioning and general health, with relatively higher scores in mental health components (2, 4, 9). These findings suggest that while physical limitations are pronounced post-amputation, mental health resilience may persist in some subgroups. Our data mirror this pattern, reinforcing the need for targeted physical rehabilitation and adaptive strategies for emotional support.
Age demonstrated a robust inverse association with several SF-36 domains, including physical functioning, role limitations, and general health. Older patients reported markedly diminished physical and role functioning, consistent with established evidence linking advanced age to reduced physical capacity and higher comorbidity burden (10). These trends underline the need for age-sensitive care plans and individualized rehabilitation programs tailored to older amputees.
Sex-related differences in HRQoL were generally non-significant; however, women showed lower scores in energy/fatigue, general health, and role emotional subscales. While these disparities did not reach strong statistical significance across all measures, they warrant further investigation, particularly given prior evidence suggesting variable psychosocial responses across genders (4, 6, 11).
Educational attainment emerged as a strong predictor of HRQoL. Patients with college-level education scored significantly higher in physical functioning, role limitations, emotional well-being, and social functioning, and reported lower levels of anxiety and depression. These findings align with evidence that education enhances health literacy, coping skills, and access to resources that promote better quality of life (12). Educational interventions, including self-management and psychoeducation, may therefore be essential components in post-amputation care models.
Income level showed minimal association with most SF-36 domains. Nonetheless, patients in the lower income group reported significantly higher anxiety scores. This suggests that socioeconomic hardship may intensify psychological distress, possibly through mechanisms such as financial insecurity, limited access to rehabilitation, and reduced support networks. Addressing economic vulnerabilities through integrated social and psychological services could mitigate these effects.
The SSI was associated with lower scores in physical functioning and role physical domains, reflecting the impact of post-surgical complications on mobility and day-to-day capacity. While the influence of SSI on other HRQoL domains was not statistically significant, its role in delaying healing and increasing disability underscores the importance of proactive infection prevention and timely management (13).
5.1. Limitations and Potential Biasess
Convenience sampling may have caused selection bias. Single-center data limits generalizability. Key variables like time since amputation were excluded, and the cross-sectional design prevents causal inference.
