Patient-Reported Mental Health Outcomes After Single-Digit Non-thumb Traumatic Amputation in Adults

Approximately 45000 traumatic digital amputations occur annually in the US, with an estimated yearly incidence of 7.5/100000 person-years.¹ The most common mechanism of traumatic digital amputation is by power saw,¹ and male adults are predominantly affected. While injury pattern and severity vary widely, the majority of traumatic amputations affect a single non-thumb digit.² 

The functional impact of a digital amputation varies, but certainly this can be substantial¹ and affect both activities of daily living and vocation.^3-7 Recently, the Finger Replantation and Amputation Challenges in Assessing Impairment, Satisfaction, and Effectiveness (FRANCHISE) Group has published extensive patient-reported outcome (PRO) information pertaining to functional outcomes after digital amputation. This included specific analysis of patients with single-digit non-thumb amputation.² In addition to a large battery of functional tests, this landmark study included the Michigan Health Questionnaire (MHQ), Short Form Health Survey (SF-36), Disabilities of the Arm, Shoulder, and Hand (DASH), and Patient-Reported Outcomes Measurement Information System (PROMIS) Upper Extremity (UE) module. While this represents an enormous amount of information pertaining to physical/functional outcomes, mental health (MH) outcomes were not the focus of this study. 

Aside from the MH items gathered within the larger MHQ and SF-36 (which were not separately analyzed by Chung et al), little data have been presented pertaining to patient-reported MH outcomes after traumatic digital amputation. As such, the aims of this study are to describe patient-reported MH outcomes after single-digit non-thumb amputation, elucidate the relationship between MH and functional outcomes, and determine which patient/injury attributes confer risk of unfavorable MH outcomes after traumatic digital amputation. 

This was a descriptive retrospective cohort study of digital amputees. After receiving approval from our institutional review board, current procedural terminology (CPT) and international classification of diseases (ICD-9/10) databases were queried for all patients undergoing digital amputation or revision amputation from April 2010 to April 2020. Medical records were reviewed for age at amputation, sex, indication for amputation, laterality, level, and number of amputated digits. Anxiety and/or depression that preceded amputation (as evidenced by formal diagnosis or documentation of a prescription for that indication) was recorded from the chart. The patient’s home address was used to determine their area deprivation index (ADI),^8,9 a measure of socioeconomic disadvantage and deprivation that has been used in several upper extremity outcome studies.^10-12 

Inclusion in this study required a single-digit non-thumb amputation sustained within the study period and age ≥18 years at the time of survey. Eligible patients were contacted by telephone. After a scripted study explanation and informed consent, each patient was asked to complete several electronically administered PRO instruments. Exclusion criteria were deceased status, inability to establish patient contact, unwillingness or inability to receive the PRO questionnaires, inability to provide informed consent, and inability to comfortably communicate in English. Consenting patients provided an email or cellular phone number by which they could receive a personalized and secure link to the study PRO instruments, which were administered remotely. The CAT questionnaires administered in this study included PROMIS Anger v1.1, PROMIS Anxiety v1.0, PROMIS Depression v1.0, PROMIS UE v2.0 (UE), and PROMIS Pain Interference v1.1 (PI). A short questionnaire recorded handedness, ethnicity, education level, and worker’s compensation (WC) status. All PRO instruments used in this study have a reference population mean of 50 and standard deviation of 10, with higher scores indicating more of the factor being measured. 

Explanatory variables were treated as dichotomous, interval, or continuous. Continuous variables were tested for normal distribution using the Shapiro-Wilk test. Normally distributed data are presented as mean (standard deviation), and data that are not normally distributed are presented as median (interquartile range). For the purposes of regression analysis, amputation level was dichotomized (0 = distal; 1 = proximal) based upon preservation (or loss) of the proximal interphalangeal joint. Comparison of means was accomplished using the 2-tailed Student t test for normally distributed variables and the Mann-Whitney U test for non-normally distributed variables. Bivariate relationships between all explanatory variables and the outcome (PROMIS) variables were assessed using linear regression. Explanatory variables with bivariate P values ≤.15 were entered into the multivariable regression. Multivariable analysis was achieved using stepwise regression. Correlation between primary and secondary outcome variables was assessed using Spearman’s rho. Statistical significance was defined as P < .05.

A priori power calculation revealed that to obtain 80% power for detection of a moderate effect size (f² = 0.15)^13,14 in a multivariable analysis with up to 3 entrant explanatory variables per model, a minimum sample of 76 subjects would be required. 

Database query yielded 513 single-digit non-thumb amputees. Eleven of these patients were known to be deceased at the time of the study, leaving 502 potentially eligible candidates. Seventy-seven (15%) patients ultimately completed follow-up questionnaires and constituted the enrolled population. Enrollment flow is detailed in Figure 1. All continuous variables were normally distributed except for “time since surgery.” 

The mean age of the enrolled population (Table 1) of single-finger non-thumb amputees at the time of amputation was 51 years, 71% were male, and mean ADI was 51. Approximately 92% of enrollees identified as white, and the injury affected the dominant side in 39% of cases. The most common amputation level was through the distal phalanx accounting for 39% of patients in this study. Table 1 describes amputation level in our enrolled population and Table 2 describes amputation level of the enrolled compared with the unenrolled population. The amputation was related to a worker’s compensation claim in 17% of cases, and followed a failed replantation attempt in 8% of cases. As outlined in Table 2, the enrolled population was significantly older, less socially deprived, and more likely to be female than the eligible patients who did not enroll in this study (Table 2).

The mean scores for the PROMIS Anger, Anxiety, Depression, UE, and PI instruments in the enrolled population are noted in Table 1. All mean values fell between 42 and 50 and were within 1 standard deviation of the reference population mean (50). Similarly, the observed standard deviations for all PROMIS outcomes measures were between 8 and 12 and approximated the reference population standard deviation of 10. A histogram of PROMIS scores is displayed in Figure 2.

Correlation among the 3 PROMIS MH domains (Anger, Anxiety, Depression) was uniformly strong (½r½ = 0.80-0.88) and statistically significant. Correlation between the PROMIS MH and functional (UE and Pain Interference) domains was statistically significant but considerably weaker (½r½ = 0.39-0.53) (Table 3).

Bivariate analysis revealed that when examined in isolation, younger age, female sex, and a WC claim were associated with higher PROMIS Anger, PROMIS Anxiety, and PROMIS Depression scores at the P <.15 level, which was our established screening cutoff for entry into the multivariable analysis (Table 4). Interestingly, amputation level was not found to have an effect on mental health outcomes. Multivariable analysis revealed that younger age and a WC claim had independent statistically significant predictive value for worse PROMIS Anger, Anxiety, and Depression scores. Female sex was also found to independently predict PROMIS Anxiety. R² for the models of PROMIS Anger, Anxiety, and Depression ranged from 0.21 to 0.25 (Table 5).

In this population of non-thumb single-digit amputees, average PROMIS Anger, Anxiety, and Depression scores were found to be lower than that of the assumed population mean of 50. While this could be interpreted to indicate very favorable outcomes in our patients, there is increasing evidence that population normal values may be substantially different among varied age groups.^15,16 As such, conclusions about absolute outcomes in this relatively young population should be made with caution.

The 3 MH outcomes were highly correlated in a positive direction. This tight correlation between PROMIS Anxiety and Depression scores has been previously observed¹⁷ by Beleckas et al in a broad general orthopedic population. While PROMIS Anger measurements have been less frequently reported in adult musculoskeletal surgery outcomes studies, strong correlation between this measure and PROMIS Depression/Anxiety has been previously documented in a large study of pediatric patients with diverse chronic health conditions.¹⁸

The observed moderate correlations among each of the 3 MH PROs and PROMIS UE/PI again recapitulates the findings of Beleckas et al who documented a nearly identical finding in a general orthopedic population. Interestingly, this group also noted that PROMIS Physical Function (PF)/PI correlated more closely to anxiety than depression. This difference, although modest, was also apparent in the current study (with substitution of PROMIS UE for PF).

In multivariable models of postoperative MH outcomes, younger age and a WC claim were each independently and significantly associated with increased anger, anxiety, and depression after amputation of single non-thumb digit. Though the models of anger, anxiety and depression were found to be otherwise nearly identical, we did find that female sex was associated with higher anxiety but not depression or anger. While this could represent a false-positive significance in the anxiety model or a false-negative finding in the depression or anger models, it is notable that this relationship between female sex and reported anxiety (and not depression) has been noted by other authors.¹⁹ 

There is substantial literature documenting that patients with a WC claim report worse outcomes after musculoskeletal intervention.^20,21 This may be attributed to the presence of a third party acting upon their trajectory of treatment and recovery, which may implicitly or explicitly incentivize the patient to perceive and/or report greater negative effects of the injury. Also, we have anecdotally found that patients who feel responsible for their own amputation tend to minimize the injury’s impact upon their lives, while patients believing that another party is responsible tend to report experiencing a greater sense of loss. 

There has been specific study of the relationship between physical disability and depressive symptoms across the spectrum of age, which is pertinent to our finding that younger age predicts a greater burden of anger, anxiety, and depression after digital amputation. In general, the linkage of physical comorbidity and depression is strong in young persons but decreases steadily with age. This means that younger patients are much more likely than older patients to experience depression resultant from development of a physical disorder like digital amputation.²² Proposed explanations for this relationship include that elderly people are more accepting of the inevitability of physical illness, resulting in the otherwise adverse psychological effects of physical disorders being “buffered.”^22,23 Similarly, older patients may be functionally “immunized” from the negative psychological effects of physical adversity by prior experience.^22,24 Furthermore, older persons are more likely than the young to cope with adversity by using acceptance and adaptation rather than trying to change their circumstances,^22,25 and they also will disengage from stressful situations in ways that reduce their emotional impact.^22,26 

Perhaps as interesting as the observed associations between patient/injury factors and MH outcomes were the candidate associations where no independent relationship was observed. Similar to our previous findings, injury characteristics, such as dominance and level, were not associated with MH outcome.²⁷ This underscores our understanding that MH outcomes are much more dependent upon the traits and situation of the person who sustains the injury rather than the characteristics of the injury itself.²⁷ The finding that a MH diagnosis before injury did not predict MH PROs may be explained by the increased likelihood that these patients with recognized MH comorbidity are more likely to be and remain under treatment than those with symptoms that have not been formally recognized and addressed. 

These observed strong correlations among PROMIS Anger, Anxiety, and Depression reflect that fundamental elements of these emotional states are likely both overlapping and co-occurrent. This is underscored by the findings of our multivariable analysis, wherein 2 factors (WC and age) dominated predictive models for each of these 3 MH outcomes. This finding could be interpreted as indicating that the anger, depression, and anxiety outcomes measures in fact measured the same outcomes and were functionally indistinct, at least in the population studied here. Indeed, Beleckas et al have commented that the orthopedic literature often groups coping abilities, anxiety, and depression together as “psychological distress” with little emphasis on differentiation between the measured outcomes.²⁸ However, they have also argued that despite being highly correlated, there is evidence that various MH PROs have different distributions in the upper extremity disease population and may have unique impact upon the course of the patient’s disease and response to treatment. Evidence in support of this position includes the finding that depression and anxiety each have significant independent predictive value for upper extremity disability,²⁹ and that only anxiety (but not depression) is associated with reduced satisfaction after carpal tunnel release.³⁰

This study includes a narrow inclusion criteria that focuses upon a relatively homogeneous population, which is relevant to the practice of most if not all hand surgeons. While traumatic fingertip amputations overall affect a more heterogeneous population, our exclusion criteria requiring comfortability communicating in the English language potentially did contribute to a less diverse patient population, which is a limitation of the study. Though we have pointed out that many of our findings are mirrored in the work of other authors examining diverse patient populations, caution should be exercised in interpreting the results of this study as it may apply to populations other than single-digit non-thumb traumatic amputees. However, we recognize that patients not comfortable communicating in English were excluded from this study. Additional limitations of this study include its modest size and retrospective nature. Furthermore, there is incomplete follow-up of eligible patients, and therefore this study is subject to response bias. Just 77 (15%) of the 502 eligible patients were able to be contacted by phone and gave permission to participate in the study. We attribute this low response rate to incomplete contact information for many patients who had sustained their injury up to a decade previously. Many patients had moved or had changed phone numbers and simply were not able to be contacted for participation. In the context of the expansive time interval covered by this study, we believe that the substantial absolute size of the included population (n = 77) is acceptable and offers useful information not previously available in the literature. Consistent with known patterns of survey response,^31,32 we included patients who were older, less deprived, and more likely to be female than the eligible group at large. We acknowledge that these findings may not be generalizable to the entire population and recognize that potentially some patients, unhappy with their surgical results, may have chosen not to participate in this study. Finally, this study is limited by the performance metrics of our chosen PROMIS outcomes measures, which are known to be subject to floor and/or ceiling effects.³² 

The clinical relevance of this study is twofold. First, it identifies a group of patients at increased risk for feelings of anger, anxiety, and depression after digital amputation. This information provides an opportunity for the surgeon to intervene with anticipatory counseling or a mental health referral. Second, our findings clarify that anger, anxiety, and depression are very likely to coexist in the same patient. When responding to a patient who exhibits 1 element of this triad, the surgeon should be aware that the other 2 elements are likely to be present, even if not obvious. For example, when encountering a patient who is angry at their employer after digital amputation, one should be aware that in addition to anger, this patient is also likely experiencing both anxious and depressive symptoms that might benefit from treatment. Though the efficacy of any intervention in this situation has not been proven and requires further study, we believe that recognizing and validating these feelings and offering a mental health referral in some case is a reasonable approach, which may result in improved patient outcomes and satisfaction.