Rule of thumb: A simple tool to estimate 1% scalp surface area

Using qualitative methods to establish the clinically meaningful threshold for treatment success in alopecia areata

PURPOSE

Traditionally, appropriate anchors are used to investigate the amount of change on a clinician-reported outcome assessment that is meaningful to individual patients. However, novel qualitative methods involving input from disease state experts together with patients may better inform the individual improvement threshold for demonstrating the clinical benefit of new treatments. This study aimed to establish a clinically meaningful threshold for treatment success for the clinician-reported Severity of Alopecia Tool (SALT) score for patients with alopecia areata (AA).

METHODS

A purposive sample of 10 dermatologists expert in AA and 30 adult and adolescent patients with AA and a history of ≥ 50% scalp hair loss were recruited. Semi-structured interview questions explored the outcome that represented treatment success to clinicians and patients. Findings were analyzed using thematic methods to identify treatment success thresholds.

RESULTS

Both informant groups confirmed scalp hair amount as the outcome of priority. Most expert clinicians considered a static threshold of 80% (n = 5) or 75% (n = 3) of the scalp hair as a treatment success. Most patient responses ranged from 70 to 90% (median: 80% of the scalp hair). Subsequently, queried patients confirmed that achieving SALT score ≤ 20 with treatment would be a success, as reflected in the Alopecia Areata Investigator Global Assessment (AA-IGA™). The novel qualitative processes used to inform this meaningful threshold reflects a clinician-then-patient process for: (a) confirmation of the patient outcome of priority; and (b) clinician input on a preliminary treatment success level for independent understanding among patients.

CONCLUSION

This qualitative investigation of expert clinicians-then-patients with AA confirmed that achieving an amount of 80% or more scalp hair (SALT score ≤ 20) was an appropriate individual treatment success threshold indicating clinically meaningful improvement for patients with ≥ 50% scalp hair loss. A qualitative investigation of a quantifiable treatment success threshold is possible through a well-designed interview process with expert clinicians and the appropriate patient population.

A Rule of Thumb for Evaluating Surface Areas of Chronic Wounds

BACKGROUND

Rapid estimation of the area of chronic wounds is clinically important. A simple method using the thumb was investigated for universal physical measurement, particularly of small and multiple wounds; the thumb surface area (TSA) was then compared with the total body surface area (TBSA).

METHODS

A cross-sectional observational study and random sampling were used to obtain the characteristics of 343 participants. Data related to handprint surface area of the thumb and palm were collected using a scanner and laptop and assessed using image software. The TSA as a percentage of TBSA was confirmed based on the traditional rule that regards palmar surface area as 1% of TBSA. Information on factors potentially influencing measurement was gathered with questionnaires to analyze correlations.

RESULTS

The left and right TSAs were on average 4.27% and 4.28%, respectively, of the palmar surface area for all participants. Multiple linear regression analysis found that male and older participants had higher TSA:TBSA proportions (sex, P = .0020; age, P < .0001). The TSA:TBSA proportion increased by age for both males (by age group, 0.0418%, 0.0426%, 0.0432%, and 0.0460%, respectively) and females (0.0400%, 0.0409%, 0.0427%, and 0.0430%, respectively).

CONCLUSIONS

Thumb size is relatively stable in relation to TBSA, lending itself to a universal method for estimating the size of chronic wounds as a percentage of TBSA. It therefore represents a convenient physical measurement for assessing the area of burns and other wounds.

A Rule of Thumb for Hand Burns: Categorization and Mapping of Proportional Surface Area Involvement

Hand burns are common and often complex injuries, requiring referral to specialist centers. The patient’s thumbprint is a rapid means of accurately assessing hand burn surface area. This study aimed to establish categories and evaluate sites of hand burn surface area in order to facilitate comparison of hand burns. Sixteen burns involving the hand and wrist among 14 patients referred to a burns center were retrospectively categorized by burn mechanism, burn thickness, and hand burn surface area. The burn surface area in the clinical record was compared with that calculated by the thumbprint method and the rule of thumb diagram. Burn surface area in the clinical record was either “1%” or “&lt;1%” in 9 of 16 cases. In contrast, the surface area was &lt;1 thumbprint (T) in six burns, two were between 1 and 5T, three were 5 to 10T, two were 10 to 20T, two were 20 to 50T, and one was greater than 50T. The median thumbprint burn surface area was 1.5T (range 0.20–80T), which corresponds to 0.05% TBSA. The hand areas with the highest burn frequency per unit area were the dorsum of the hand and dorsum of the index finger, with relative sparing of the palm and palmar surface of the digits. Hand burns surface area varies widely, and thumbprint evaluation with categories and mapping allows finer distinction between the surface area proportions and specific sites involved, even in a small series of hand burns.

Variational Principle of Least Psychomotor Action: Modelling Effects on Action from Disturbances in Psychomotor Work Involving Human, Cyborg, and Robot Workers

Optimal psychomotor work can be expressed in terms of the principle of least psychomotor action (PLPA). Modelling psychomotor action encompasses modelling workers, work, and interactions between them that involve different types of situated entropy. Modelling of psychomotor workers encompasses three types of workers: human, cyborg, and robot. The type of worker and the type of work interact to affect positioning actions, performing actions, and perfecting actions undertaken in psychomotor tasks. There are often disturbances in psychomotor work, for example due to weather conditions, which have a determining influence on what work can be undertaken with least psychomotor action by different types of workers. In this paper, findings are reported from a study focused on the modelling disturbances in psychomotor work. Five contributions are provided. First, a heuristic framework for modelling disturbances and their effects is provided. In addition to PLPA and situated entropy, this framework encompasses Markov processes, the theory of perturbations, and calculus of variations. Second, formulae and ratios are provided for heuristic modelling of effects on internal action (S_int) from disturbances to psychomotor work. Third, formulae and ratios are provided for heuristic modelling of effects on external action (S_e). Fourth, examples are provided of heuristic modelling of disturbances in psychomotor work. Fifth, formulae and examples show how task complexity can be modelled heuristically in terms of microstates across the cyber domain and the physical domain of cyber-physical systems. Overall, the study reported in this paper addresses variational aspects of PLPA.