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Anais Brasileiros de Dermatologia

Print version ISSN 0365-0596

An. Bras. Dermatol. vol.84 no.6 Rio de Janeiro Nov./Dec. 2009 



Evaluation of patients' learning about the ABCD rule: a randomized study in southern Brazil



Karen Reetz MüllerI; Renan Rangel BonamigoII; Thayse Antoniolli CrestaniIII; Gisele ChiaradiaIV; Maria Carolina Widholzer ReyV

IMD, graduated from the Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA) – Porto Alegre (RS), Brazil
IIAdjunct Professor-3 and Head of the Department of Dermatology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA) – Porto Alegre (RS). Lecturer of the Graduate Program in Pathology: Master's and Ph.D. degrees, UFCSPA. Ph.D. in Medical Sciences from the Universidade Federal do Rio Grande do Sul (UFRGS) – Porto Alegre (RS), Brazil.
IIIMedical student from the Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA) – Porto Alegre (RS), Brazil
IVResident physician, Department of Dermatology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA) – Porto Alegre (RS), Brazil
VPreceptor of the Department of Dermatology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA) – Porto Alegre (RS). Master's degree in Pathology from the Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA) – Porto Alegre (RS), Brazil

Mailing Address




Background: the ABCD rule is used to guide physicians, health care professionals and patients to recognize the main characteristics of suspicious skin lesions for melanoma. In Brazil there are no studies to validate the use of the ABCD rule by patients after instructions given by dermatologists.
to evaluate the learning of the ABCD rule by patients at a dermatology center of reference in the Southern region of Brazil.
a randomized study, with 80 outpatients. The following were evaluated: sex, age, level of schooling, monthly income and access to means of communication. The intervention group received instructions regarding the use of the ABCD rule and the control group did not. Both groups were evaluated at three points in time (baseline; outside the office; and in the doctor's office, 15 days later) regarding their answers about a panel of photographs. The level of significance used was p < 0.05 and a power of 0.80.
the group that received information answered correctly regarding the diagnosis of melanomas more often
compared to the control group (p < 0.01).Except access to radio broadcasting, which had a positive influence of the results (p < 0.05), the other variables evaluated did not influence the results.
the ABCD rule can be used to train patients, above the age of 17 years, to identify changes that suggest melanoma. This learning is independent of sex, level of schooling, monthly income and access to means of communication, except the radio.

Keywords: diagnosis; melanoma; patients




Melanoma represents 3 to 5% of skin neoplasms; however, its lethality is higher than basal cell and squamous cell carcinomas. Moreover, its incidence has grown in many countries in the past years, including Brazil. The Brazilian state with the highest incidence of melanoma is Santa Catarina, with 8.61 cases for 100,000 males, followed by the state of Rio Grande do Sul, with 8.2 cases for 100,000 males.1

According to estimates of incidence of cancer in Brazil, for 2008, 2950 new cases of melanoma were expected in males and 2970 new cases in females.2 The efforts to revert this trend have been focused on primary prevention, through programs to orient the population.3

Cutaneous melanoma is located on the skin surface, and thus could be detected, or at least suspected, by physicians and lay people.4,5 In a Brazilian study, 75% of a sample of melanoma cases had their lesion first detected by lay individuals (by patients themselves, spouses, other relatives or friends). 6

The early detection of melanoma may be facilitated by applying the "ABCD Rule", in which A corresponds to asymmetry; B to border irregularity; C to color variation; and D to diameter greater than 6 mm.5,7

There are no studies in Brazil about the learning process of the ABCD rule by patients after receiving medical information. This process may be influenced by education and socioeconomic situations.

This article aims to assess the ability of patients to suspect a diagnosis of melanoma, after receiving information on the ABCD rule, in a public healthcare service in the Southern region of Brazil, where the population is exposed to a significant risk of skin cancer.



The Research Ethics Committee of the Universidade Federal de Ciências da Saúde de Porto Alegre approved the methodology and ethics of the study.

It is a cohort, prospective and randomized study. Literate patients, aged over 12 years were enrolled. Patients with skin cancer upon medical visit or with past history of skin cancer were excluded. The following variables were analyzed: age, sex, family income, schooling, access to television, radio, internet and/or printed newspapers. The outcome was the correct identification of melanomas in panels of skin lesions, after oral, written and visual explanation (presentation of photographs) about the ABCD rule, always given by the same physician. The choice of the group of photographs was considered appropriate for the study by the dermatology lecturers of the UFCSPA.

A total of 80 outpatients were selected and randomized, and 40 received information and an explanatory material about the ABCD rule (intervention group or group A) and 40 did not receive any information or material about the ABCD rule (control group or group B).

Before the initial intervention (testing time 1 or baseline), all 80 patients were given a sheet with eight color photographs and no legends, containing melanoma lesions, benign melanocytic lesions and non-melanocytic lesions, to assess and answer which would be skin cancer type melanoma.

Testing time 2 was conducted with answers for a new group of photographs (different from the previous pictures, but with same difficulty level) in a setting outside the outpatients' clinic (patients took the material home), which were given back upon return to the clinic 15 days later.

Testing time 3, a fortnight later, was carried out with answers to a third group of photographs (different from the previous two groups, but with same difficulty level) at the outpatients' clinic again.

In each test, among the eight photographs presented, three corresponded to melanoma lesions. All patients of the control group also received information and the explanatory material, but after conclusion of the three tests.

In addition to assessing the ability of patients to suspect a diagnosis of melanoma after receiving information on the ABCD rule, the other variables described were evaluated in relation to the outcome.

The calculi to define the size of the sample were based on a probable rate of correct answers of 60% in the intervention group and of 20% in the control group, with significance level of p < 0.05 and power of 80%.

The statistical analysis included, whenever necessary, description of simple and relative frequencies, standard deviation, median, mean estimators, Pearson chi-square test, Fisher's exact test, and Mann Whitney test.

The data were statistically treated using the software SPSS 13.0 (Statistical Package to Social Sciences for Windows).



Considering the total sample (n=80), 63.3% of patients were female. The mean age was 46.7 years (SD = 15.5), raging from 17 to 80 years. As to income, the bracket over R$ 1.000,00 predominated and amounted to 53.8% of patients. Regarding schooling level, incomplete junior school was the most expressive, with 26.3%, followed by complete junior school and complete high school (22.5% of patients in each level). The variables age, sex, income and schooling did not present significant difference between the two groups (p > 0.05).(Table 1)



Considering distribution of frequencies of variables investigating access to information, the total sample showed that 96.3% of patients had access to television, 86.3% to radio, 76.3% to newspapers and 31.3% had access to the internet.(Table 2)



Based on the results observed in Table 3, obtained through the Pearson chi-square test, it was verified that on test 1 (baseline, before intervention) there was no statistically significant association (p > 0.05), indicating that the number of right answers in both groups presented a similar distribution.



In test 2 results, a statistically significant association was detected (p < 0.01); in that, the intervention group was significantly associated to three right answers, whereas, in the control group, the association was verified with zero, one and two right answers.

Evaluating test 3, the intervention group presented a significant association with three right answers and, in the control group, the association was verified with zero and one right answers (p < 0.001).

Directing the analysis, the variability between tests 1 and 3 was compared in cases and controls as to the maximum number of right answers (3). Comparing the difference in number of patients who had three right answers in tests 1 and 3, in both groups, there was a statistically significant difference in chi-square test for comparisons of proportions ( 2calc = 8.548; p = 0.0035), so that intervention group presented a significantly higher number of patients with three right answers, as compared to the control group.

In the intervention group, the variability was 75. 6% (n = 31), that is, in test 1, five patients had three right answers, whereas, in test 3, 36 patients presented three right answers. In the control group, the variability between the number of three right answers between tests 1 and 3 was 37.9% (n = 11), i.e., in test 1, nine patients achieved three right answers and, in test 3, 20 patients got the correct answer.

The differences in number of patients - from 5 to 36, in intervention group, and from 9 to 20, in the control group - were statistically significant. The percentage difference was 37.7% (95% CI - 14.25; 56.24).

Except for the variable access to radio, all others did not show statistically significant differences as to number of right answers between the groups, when using mean, median and standard deviation.

In regard to access to information via radio, there was a significant difference in the number of right answers in the intervention group (p < 0.05). The patients who informed having access presented numbers of correct answers significantly higher than the group of patients who had no such access (Mann Whitney test, p = 0.032).



Although Brazil has presented progressively higher incidence rates of cutaneous melanoma in the past two decades, there are no national studies on the use of self-examination for early detection of the disease.8-11 In particular, little is known about the potential use of the ABCD rule by Brazilians, despite its use for academic and lay teaching.

This randomized study conducted in Porto Alegre, Brazil, aimed at three testing times. The first moment, baseline, was to check if knowledge before intervention was similar in cases and controls.

The second testing time, when intervention had been performed in one of the groups, aimed to demonstrate what remained of learning with probable influence of the environment of each patient, since the test was answered at home or in other places different from the medical office. And, the third testing time was designed to measure the ability to correctly answer after recalling information received 15 days before, on initial intervention.

With this scenario, the cohort study demonstrated that the ABCD rule to diagnose cutaneous melanoma can be employed by literate patients, aged over 17 years, regardless of sex, monthly income, schooling level and access to information, through television, newspaper and internet.

Access to information by means of radio seems to be an independent factor that increases the ability to use the rule correctly (p < 0.05), maybe for this medium favoring a more prolonged contact during the day, and information being repeated many times.

It is interesting to observe that the intervention group had more frequent right diagnoses of melanoma, besides presenting more variability before and after intervention (p < 0.05).

The present study evaluated a short follow-up cohort. Hence, the study is limited as to capacity to predict permanence of long-term learning.

It is fundamental to expand teaching of this rule to the Brazilian population and to maintain learning, including the topic in health-related subjects in schools, workplaces and other institutions, and disseminating it in different media, particularly radio broadcasting.



The study demonstrated, in a population sample of the Southern region in Brazil, the pertinence to use the ABCD rule to correctly identify alteration suggesting melanoma. Learning about the rule does not depend on sex of patients, is observed in different schooling levels and monthly incomes, and seems to be facilitated for those that have access to radio as a communication medium.



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10.  Carli P, De Giorgi V, Nardini P, Mannone F, Palli D, Giannotti B. Melanoma detection rate and concordance between self-skin examination and clinical evaluation in patients attending a pigmented lesion clinic in Italy. Br J Dermatol. 2002;146:261-6.         [ Links ]

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Mailing Address:
Karen Reetz Müller
Rua Felicíssimo de Azevedo, 290 – Ap. 302
Bairro São João
90540 110 Porto Alegre – RS, Brasil

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