Evaluation of impairment of quality of life

Since no quality of life questionnaire is available for evaluation of impairment of quality of life due to a diagnostic intervention we used the following methods for assessment:
1. 5-step ordinal scale ranging from 1 to 5. 1 represents the lowest and 5 the highest impairment in quality of life due to the necessity of regular follow-up.
2. Willingness-to-pay as quality of life instrument [26-28].
Wtp in the classical sense is a parameter for the evaluation of quality of life by asking the patients how much money they would be willing to pay for an imaginary therapy which would be able to release them from their disease. In theory, the more the patients are willing to pay, the more they are impaired and vice versa. This principle was adopted by using following self-developed question (question asked in German):

Additionally, quality of life impairment was assessed for patients with a history of malignant melanoma (question asked in German):

Again, percentages of monthly income were calculated. Using these data, utility values could be calculated for comparison of impairment in quality of life with other dermatological diseases [27, 28, 30].
Utilities are cardinal values which are assigned to each health state on a scale that is established by assigning a value between 0 and 1. In our case, wtp could range between 0% of monthly income (no reduction of quality of life) and 100% of monthly income (maximum reduction of quality of life). The utility values reflect the quality of the actual patients’ health status and allow morbidity to be combined into a single weighted measure.

Statistical methods

Descriptive statistics

Descriptive statistics are presented for each assessment concerning data of study centers, patients’ demographics, evaluation of confidence, and quality of life impairment. For categorical data (e.g. sex, profession), absolute and relative frequencies (n, %), for continuous data (wtp) and qualitative ordinal data (ordinal scale) mean values and standard deviations are given.

Inferential analysis

Ordinal measures (confidence, quality of life impairment) were tested using non-parametric methods: comparison between newcomers and follow-up patients was performed using Wilcoxon rank sum test. Confidence in different diagnostic methods was tested by individual comparison using Wilcoxon matched-pairs signed-rank test.
Wtp (absolute and relative values) for different methods were compared individually with paired-sample t-tests. Differences in wtp between newcomers and follow-up patients were detected by t-tests for independent samples. For all tests the two-sided approach was chosen. Spearman correlation analysis was used to detect potential correlation between patients’ income and wtp.

Results

Study centers

14 study centers were involved: 13 private dermatological practices and the department of Dermatology of the University of Regensburg, Bavaria, Germany.

Assessments in investigators

Mean age of examiners was 42 years ranging from 32 to 62. 12 (86%) were male. Mean experience in HHD was 7.7 years (ranging from 2 to 15), 3 years in DD (8 months to 7 years).

Survey

The survey was performed from September to December 2001. 146 of 210 (response rate 69.5%) questionnaires were returned, 143 (98%) of them could be used for analysis. 3 patients had to be excluded due to age under 18.

Assessments in patients

Mean age was 37 ± 11.3 years ranging from 19 to 75. 60 patients (42%) were male and 83 (58%) female. Profession groups were as follows: 46.8% employees, 12.6% civil servants, 11.9% housewives, 9.1% selfemployed, 7% workers, 3.5% pensioners, 1.4% unemployed, and 0.7% in education.
Mean income per household per month after taxes was  2602.– ± 1332.– (ranging from 256.– to 6136. –). 35 patients (25%) were newcomers and 106 (75%) repeat visits for follow-up of MN. There were no statistically significant differences between distributions of age, sex, and professions between newcomers and repeat visit patients.
13 patients (9.1%) had less than 10 MN, 49 (33.8%) between 10 and 50, 46 (32.4%) between 50 to 100, 21 (14.8%) between 100 and 200, and 14 (9.9%) more than 200. 18 patients (13%) had a malignant melanoma history. At least one MN was excised in 81 (57%) patients in the survey.
After examination of MN a regular follow-up was recommended by the investigator for 126 (88%) patients. Patients without a malignant melanoma history estimated their risk for the development of malignant melanoma at a mean of 23.3% ± 21.6 which was clearly lower than for patients with a malignant melanoma history: 42.1% ± 24.6.

Confidence in diagnostic methods

1. Ordinal scale. Confidence in NEI was at a mean of 1.89 ± 0.95 (newcomer: 2.06 ± 0.96; repeat consulations: 1.72 ± 0.96), in HHD 2.82 ± 0.94 (2.96 ± 0.91; 2.7 ± 0.96), in DD 4.45 ± 0.69 (4.45 ± 0.77; 4.51 ± 0.56), and 4.71 ± 0.51 (4.69 ± 0.54; 4.72 ± 0.48) in TD (see figure 1 and Table I).

Confidence in a hypothetical method promising 100% safety

Mean wtp was 5.0% ± 7.8 of monthly income (92.10 ± 76.10) and therefore markedly higher than for the highest wtp assessed for a diagnostic method available at present. After transforming wtp data of each patient given for NEI, HHD, DD, and TD to percentages of 100% method, individual standardized wtp-values could be calculated. Mean confidence (in terms of standardized wtp) in NEI was only 14.9%, in HHD 24.8%, in DD 58,4%, and in TD 60% (see figure 3 and Table I).

Evaluation of impairment of quality of life

1. Ordinal scale

Mean value for impairment of quality of life due to regular follow-up was 1.7 ± 1.1 and therefore a slight impairment in quality of life can be suggested. There was no statistically significant difference between newcomers and repeat consultation patients.

2. Willingness-to-pay

Mean relative wtp for hypothetically avoiding a regular follow-up was 0.5% ± 0.8 (absolute wtp: 12.00 ± 17.19) corresponding to a utility value of 0.995. Mean relative wtp to hypothetically dismissing the history of malignant melanoma (assessed in patients with malignant melanoma history only) was observed as 4.7% ± 8.3 (89.00 ± 131.50) with a corresponding utility value of 0.953.

Discussion

For the first time in dermatological research, various diagnostic methods for the detection of malignant melanoma and monitoring of MN were evaluated from the patient’s point of view. Both assessments used for evaluation (ordinal scale and willingness-to-pay) provided identical results showing a statistically significant increase in confidence from NEI to TD. In principle, this fact confirms scientific knowledge: sensitivity is lowest for NEI and increases using dermoscopical methods [3-5]. Therefore implementation of dermoscopy is inevitable for dermatologists to ensure both optimal diagnostic accuracy and best patient’s confidence. Nevertheless, the diagnostic power of experienced investigators was clearly underestimated by the patients. The markedly higher confidence of patients in dermoscopical methods using computer techniques (DD and TD were judged about twice as safe as HHD) might represent higher confidence in technique than in human beings in our times.
Furthermore, and this – from our point of view – is an even more important result, there is a distinct gap between patients’ level of confidence for diagnostic methods available at present and a hypothetical tool with 100% safety. It could be suggested that the type of assessment (comparison to a hypothetical 100%-method) could influence the patients’ answers and it could be expected that patients want to pay most for 100% safety. Still, the extent of the difference with existing dermoscopical methods was surprising. Compared to this hypothetical method, TD (which uses the knowledge and experience of a specialist in dermoscopy) achieved only 60% confidence, HHD even only 24.8%. The power of present diagnostic methods was clearly underestimated by the patients. It might be suggested that this false impression of diagnostic power also influences patient’s compliance which indeed is extremely low in follow-up programs: mean annual drop-out rate is described as 11.2% during follow-up among patients with thin melanomas for whom follow-up could be proven to be essential for survival [31]; from patients offered a regular follow-up of their MN for prevention of malignant melanoma, only 46.2% joined the program [32]. An improvement of compliance by increasing information about the diagnostic power of present diagnostic methods, especially when using dermoscopy, seems to be necessary.

There was no difference in confidence between newcomers and repeat consultation patients. This underlines the necessity for better information for patients, concerning the power of dermoscopy, since experience in examinations with the repeat consultation patients did not positively influence confidence. In contrast to patients’ underestimation of the power of diagnostic methods for the detection of malignant melanoma, their own risk for the development of malignant melanoma was overestimated (e.g. patients with a malignant melanoma history estimated their risk as 42.1%, whereas the true risk is about 3% [33, 34]. Therefore patients’ visits at regular follow-up seem to be more motivated by fear of malignant melanoma than by confidence in the diagnostic methods. It should be underlined that the assessment of wtp was exclusively used to measure confidence in diagnostic methods. The data should not and cannot be used as a basis for fixing prices for DD or TD, especially regarding the fact that patients with a lower average income were willing to pay less money per method (in terms of absolute values).

Concerning quality of life, patients feel only slightly impaired due to the necessity for regular follow-ups. Utility values as calculated from wtp allow a comparison of levels of quality of life impairment to other dermatological conditions. According to data evaluated with the Dermatology Life Quality Index (DLQI) [35], one of the most frequently used quality of life questionnaires in dermatology, utility values provide similar quality of life impairments: patients with chronic skin diseases, especially if visible to the public, are clearly more impaired than patients with malignant melanoma (see Table II).

The following conclusions can be drawn from our study:

1. This study was performed without any influence on routine information for patients. Results therefore represent patients’ actual knowledge of dermoscopical methods in daily dermatological practice.
2. Patients’ confidence was highest for TD including the opinion of a specialist in dermoscopy. The diagnostic power of HHD was clearly underestimated.
3. Confidence for HHD, DD, and TD – the best methods available at present – was at least 40% below a hypothetical method promising 100% safety. A lack of information in patients of the diagnostic power of dermoscopy has to be stated.
4. Since clinical efficacy and cost-effectiveness for follow-up programmes are highly dependent on compliance, more patient information is necessary concerning the type and accuracy of present diagnostic tools for detection of malignant melanoma and follow-up of MN. n

References

1. MacKie R. An aid to the preoperative assessment of pigmented skin lesions of the skin. Br J Dermatol 1971; 85: 232-8.

2. Fritsch P, Pechlaner R. Differentiation of benign to malignant melanocytic lesions using incident light microscopy. In: Ackerman AB, Mihara I. Pathology of malignant melanoma. New York: Masson 1981: 301-12.

3. Pehamberger H, Binder M, Steiner A, Wolff K. In vivo epiluminescence microscopy: improvement of early diagnosis of melanoma. J Invest Dermatol 1993; 100: 356-62.

4. Meyer J. Systematic review of the diagnostic accuracy of dermatoscopy in detecting malignant melanoma. Med J Aust 1997; 167: 206-10.

5. Kittler H, Pehamberger K, Wolff K, Binder M. Diagnostic accuracy of dermoscopy. Lancet Oncol 2002; 3: 159-65.

6. Pehamberger H, Steiner A, Wolff K. In vivo epiluminescence microscopy of pigmented skin lesions. I. Pattern analysis of pigmented skin lesions. J Am Acad Dermatol 1987; 17: 571-83.

7. Menzies SW, Ingvar C, McCarthy WH. A sensitivity and specificity analysis of the surface microscopy features of invasis melanoma. Melanoma Res 1996; 6: 55-62.

8. Argenziano G, Fabbrocini G, Carli P, De Giorgi V, Sammarco E, Delfino M. Epiluminescence microscopy fpr the diagnosis of doubtful melanocytic skin lesions. Comparison of the ABCD rule of dermatoscopy and a new 7-point checklist based on pattern analysis. Arch Dermatol 1998; 134: 1563-70.

9. Stolz W, Braun-Falco O, Bilek P, Landthaler M, Burgdorf WHC, Cognetta AB. Color atlas of dermatoscopy. Blackwell science, Berlin 2002, 2^nd edition.

10.  Schindewolf T, Schiffner R, Stolz W, Albert R, Abmayr W, Harms H. Evaluation of different image acquisition techniques for a computer vision system in the diagnosis of malignant melanoma. J Am Acad Dermatol 1994; 31: 33-41.

11. Horsch A, Stolz W, Neiss A, Abmayr W, Pompl R, Bernklau A, Bunk W, Dersch DR, Glaessl A, Schiffner R, Morfill G. Improving early recognition of malignant melanomas by digital image analysis in dermatoscopy. Stud Health Technol Inform 1997; 43: 531-5.

12. Binder M, Kittler H, Seeber A, Steiner A, Pehamberger H, Wolff K. Epiluminescence microscopy-based classification of pigmented skin lesions using computerized image analysis and an artificial neural network. Melanoma Res 1998; 8: 261- 6.

13. Menzies SW. Automated epiluminescence microscopy: human vs machine in the diagnosis of melanoma. Arch Dermatol 1999; 135: 1538-40.

14. Pompl R, Bunk W, Horsch A, Abmayr W, Morfill G, Brauer W, Stolz W. Computer vision of melanocytic lesions using MELDOQ. Skin Res Technol 1999; 5: 150.

15. Seidenari S, Pellacani G, Giannetti A. Digital video-microscopy and image analysis with automatic classification for detection of thin melanomas. Melanoma Res 1999; 9: 163-71.

16. Glaessl A, Schiffner R, Walther T, Landthaler M, Stolz W. Are dermatologists in private practice interested in teledermatological services? Stud Health Technol Inform 1999; 64: 185-91.

17. Piccolo D, Smolle J, Wolf IH, Peris K, Hofmann-Wellenhof R, Dell’Eva G, Burroni M, Chimenti S, Kerl H, Soyer HP. Face-to-face diagnosis vs telediagnosis of pigmented skin tumors: a teledermoscopic study. Arch Dermatol 1999; 135: 1467-71.

18. Glaessl A, Schiffner R, Walther T, Landthaler M, Stolz W. Teledermatology – the requirements of dermatologists in private practice. J Telemed Telecare 2000; 6: 138-41.

19. Argenziano G, Soyer HP, De G, Piccolo D. Dermoscopy. An interactive atlas. EDRA, Milano 2000.

20. Braun RP, Meier M, Pelloni F, Ramelet AA, Schilling M, Tapernoux B, Thurlimann W, Saurat JH, Krischer J. Teledermatoscopy in Switzerland: a preliminary evaluation. J Am Acad Dermatol 2000; 42: 770-5.

21. Stolz W, Schiffner R, Pillet L, Vogt T, Harms H, Schindewolf T, Landthaler M, Abmayr W. Improvement of monitoring of melanocytic skin lesions with the use of a computerized acquisition and surveillance unit with a skin surface microscopic television camera. J Am Acad Dermatol 1996; 35: 202-7.

22. Kittler H, Seltenheim M, Dawid M, Pehamberger H, Wolff K, Binder M. Frequency and characteristics of enlarging common melanocytic nevi. Arch Dermatol 1999; 136: 316-20.

23. Kittler H, Pehamberger H, Wolff K, Binder M. Follow-up images of melanocytic skin lesions with digital epiluminescence microscopy: patterns of modifications observed in early melanoma, atypical nevi and common nevi. J Am Acad Dermatol 2000; 43: 467-76.

24. Menzies SW, Gutenev A, Avramidis M, Batrac A, McCarthy WH. Short-term digital surface microscopic monitoring of atypical or changing melanocytic lesions. Arch Dermatol 2001; 137: 1583-9.

25. Kittler H, Binder M. Risk and benefits of sequential imaging of melanocytic skin lesions in patients with multiple atypical nevi. Arch Dermatol 2001; 137: 1590-5.

26. Finlay AY, Coles EC. The effect of severe psoriasis on the quality of life of 369 patients. Br J Dermatol 1995; 132: 236-44.

27. Lundberg L, Johannesson M, Silverdahl M, Hermansson C, Lindberg M. Quality of life, health-state utilities and willingness to pay in patients with psoriasis and atopic eczema. Br J Dermatol 1999; 141: 1067-75.

28. Schiffner R, Brunnberg S, Hohenleutner U, Stolz W, Landthaler M. Willingness to pay and Time trade off-useful indicators for the assessment of quality of life and patient satisfaction in patients with port wine stains. Br J Dermatol 2002; 146: 440-7.

29. Schiffner R, Schiffner-Rohe J, Gerstenhauer M, Hofstädter F, Landthaler M, Stolz W. Willingness-to-pay and time-trade-off: sensitive to changes of quality of life in psoriasis patients ? Br J Dermatol in press.

30. Ellis ChN, Reiter KL, Wheeler JCW, Fendrick AM. Economic analysis in dermatology. J Am Acad Dermatol 2002; 46: 271-83.

31. Kittler H, Weitzdorfer R, Pehamberger H, Wolff K, Binder M. Compliance with follow-up and prognosis among patients with thin melanomas. Eur J Cancer 2001; 37: 1504-9.

32. Schiffner R, Schiffner-Rohe J, Landthaler M, Stolz W. Long-term dermoscopical follow-up of melanocytic nevi: clinical outcome and patient`s compliance. Br J Dermatol in press.

33. Landthaler M, Braun-Falco O, Bernreiter F, Hölzel D. Multiple primary malignant tumors in patients with malignant melanoma of the skin. Hautarzt 1992; 43: 11-5.

34. Schmid-Wendtner MH, Baumert J, Wendtner CM, Plewig G, Volkenandt M. Risk of second primary malignancies in patients with cutaneous melanoma. Br J Dermatol 2001; 145: 981-5.

35. Finlay AY, Khan GK. Dermatology Life Quality Index (DLQI) a simple practical measure for routine clinical use. Clin Exp Dermatol 1994; 19: 210-6.