Clinical scoring scales in thyroidology: A compendium.

This compendium brings together traditional as well as contemporary scoring and grading systems used for the screening and diagnosis of various thyroid diseases, dysfunctions, and complications. The article discusses scores used to help diagnose hypo-and hyperthyroidism, to grade and manage goiter and ophthalmopathy, and to assess the risk of thyroid malignancy.

INTRODUCTION

Clinical scores have traditionally been used in thyroidology to help in the diagnosis of thyroid dysfunction. The time honored Wayne's score and Billewicz score are well known to older generations of endocrinologists, for their utility in the clinical diagnose of hyperthyroidism and hypothyroidism, respectively.

Sadly, however, these scores do not find place in current textbooks of surgery or medicine, having been discarded as being too old fashioned. Current students of medicine therefore do not have easy access to these, and to newer scoring systems in thyroidology.

Newer clinical scores and grading systems have also been developed by workers, highlighting the numerous diagnostic developments and advances in the field. Results from imaging studies such as ultrasound are also used in grading thyroid malignancy.

This compendium seeks to bring together, and comment upon, the various scoring and grading systems used in clinical endocrinology. It is hoped that this collation will be of use to endocrinologists, physicians, and all workers in the field of thyroidology.

GOITER

The diagnosis of goiter is a clinical one arrived at by inspection and palpation. The presence of goiter does not necessarily indicate thyroid dysfunction.

The World Health Organization has classified goiter in a simple, objective manner, into three grades.[1] This classification can be used to grade, compare, and monitor thyroid enlargement [Table 1], with minimal inter- and intraobserver bias.[2]

Table 1

WHO classification of Goiter

HYPERTHYROIDISM

Grave's disease is used to describe the diffuse hyperplasia of the thyroid gland. The signs and symptoms of Grave's disease can be classified into three groups.[3]

The first groups of symptoms occur because of hyperfunctioning of the thyroid gland and increased catecholamine sensitivity. The second group related to the enlargement of the thyroid, i.e., goitre and its accompanying signs such as thyroid bruit. The third constellation of symptoms and signs is the eye signs, which are a long list of eponymous conditions, dreaded by medical students. In addition, there are miscellaneous clinical features, affecting the skin, muscles and other systems.[3] These symptoms and signs have been used to prepare a simple clinical score for diagnosis and screening.

Wayne's Index is more than half a century old,[4] but has shown remarkable success in helping diagnose hyperthyroidism [Table 2].

Table 2

Wayne's Index- Showing the scoring of signs and symptoms for the diagnosis of hypothyroidism

Nine symptoms and 10 signs are listed, each with differential weightage in scoring. The signs are scored both positively and negatively, i.e., absence of some signs (but not all) gives negative marking. Similarly, two symptoms, i.e., decreased appetite and preference for heat, have negative scores.

The score ranges from + 45 to -25. A score greater than 19 implies toxic hyperthyroidism, while a score less than 11 implies euthyroidism, A score between 11 and 19 is equivocal. Though arrived at by trial and error, it has shown a diagnostic accuracy of 85%.

Wayne's Index was earlier used to help to diagnose hyperthyroidism and limit the number of investigations required.[4] At present, its value lies in its emphasis on clinical thyroidology, and its utility in explaining the clinical features of Grave's disease to thyroid practitioner.

OPTHALMOPATHY

The clinical activity score (CAS), for Grave's opthalmopathy, published in 1997,[5] has become a widely accepted tool to help decide the management of the condition. Grave's opthalmopathy is a biphasic disease, with an initial phase of active inflammation, followed by a “burnt out” phase with stable proptosis and impaired eye muscle mobility.

The CAS, which is based on four classical signs of inflammation (pain, redness, swelling and impaired function), consists of 10 equally weighted items [Table 3]. The total CAS may range from 0 to 10. The higher the CAS, the greater is the response to immunosuppression. A CAS ≥4 implies an active inflammatory stage of Grave's opthalmopathy. Using this CAS cut-off, a specificity of 86%, sensitivity of 55%, positive predictive value of 80%, and a negative predictive value of 64% have been reported in predicting therapeutic outcome. CAS does not differ in duration of disease.[5]

Table 3

Point system used for the clinical activity score

CAS is able to predict therapeutic outcome based on classical signs and symptoms of inflammation. The sign of “heat” is not used in CAS as it is difficult to detect subtle rises of orbital temperature without special instruments.

A study on CAS[5] found that intraobserver variance was minimal for pain- related symptoms. It was higher for redness of the conjunctiva, which should be diffuse, and cover at least one quadrant to be defined as inflammatory. The CAS is purely clinical, and helps select appropriate therapy for patients with Grave's opthalmopathy.

The NOSPECS classification has been used for over a decade to grade the changes seen in thyroid opthalmopathy in an objective manner. The NOSPECS scores the disease based on soft tissue involvement, corneal involvement, and sight loss [Table 4].[6]

Table 4

NOSPECS classification

It is an objective method of assessing disease progression, rather than inflammation. It can be used to grade and monitor patients with minimal interobserver variability.

The NOSPECS classification is also a simple mnemonic which helps emphasize the clinical features of thyroid disease, while making it simple for medical students to remember them.

In passing, one may mention another mnemonic related to thyroid disease. The TEARS mnemonic is useful for remembering the initial management of the condition [Table 5].[7]

Table 5

TEARS mnemonic for remembering initial management

HYPOTHYROIDISM

The Billewicz score utilizes 8 symptoms and 6 signs to assess the thyroid status, and diagnose hypothyroidism. In a detailed study on 256 euthyroid controls, and hypothyroid patients, 13 symptoms and 8 signs were studied. Initially 14 symptoms and signs were selected and weighted differentially, based on the frequency of their occurrence in hypothyroid patients [Table 6].[8]

Table 6

Billewicz diagnostic index[6]

The score may range from + 67 to – 47, with the highest weightage being given to a sluggish ankle jerk and slow movements. Billewicz et al. do not forget to prescribe an effective manner in which to elicit these signs and symptoms, in order to minimize interobserver variability.[8]

Diminished sweating is assessed in a warm room or a centrally heated hall (Billewicz practiced in Aberdeen, Scotland). Dry skin is defined as dryness of skin noted spontaneously, or requiring treatment. Cold intolerance implies a preference for a warm room, extra clothing, or bed clothing. The weight increase is scored as present if the patient reports a recorded increase in weight or complains of tightness of clothing. Similarly, constipation is scored as present if the patient reports a change in bowel habit or use of laxative Hoarseness is assessed in both speaking voice and singing voice, while paresthesia are scored based on subjective sensations. Deafness is defined as progressive improvement of hearing.

Slow movements are noted while observing the patient removing and replacing a buttoned garment. Correction of skin is assessed over the hands, forearms, and elbows, with the examiner checking for roughness and thickening of skin. Cold skin is assessed by comparing the patient's hand temperature with that of the examiners. Periorbital puffiness is defined if it obscures the curve of the malor bone. Billewicz et al. recommend counting the pulse for a 30-s period, and report bradycardia of the pulse <75/min. They elicit the ankle jerk with the patient kneeling on a chair, grasping its back.[8]

A score of +25 or more suggests hypothyroidism, while a score of -30 or less excludes the disease.[8] The score can be used as a screening tool, especially in psychiatric patients. The utility of the Billevicz score lies in its ability to teach students about the clinical features of the disease.

A simple postal questionnaire has also been used to assess in the follow-up of patients treated with radioactive iodine.[9] This is a cost-effective method of screening for hypothyroidism, and can help increase the rate of detection of this condition in patients at risk [Table 7].

Table 7

Postal formulary used to elicit symptoms of hypothyroidism

Initially designed as a seven-question list, it was later expanded to nine questions, all to be answered as yes or no. Patients with symptoms are investigated for thyroid function, while asymptomatic ones may have investigations deferred. This leads to considerable cost-saving.[9]

The Billewicz score and the postal questionnaire mentioned above were studied at a time when modern methods of diagnosing hypothyroidism were not available.

Zulewski et al. [Table 8] set out to reevaluate the classical signs and symptoms of hypothyroidism in the light of modern laboratory tests. They measured clinical scores, thyroid function, and tissue thyroid status (using ankle reflex relaxation time [ART] and total cholesterol, in 50 hypothyroid, 93 subclinically hypothyroid, 67 treated hypothyroid, and 189 euthyroid female adults.[10]

Table 8

Zulewski's clinical score for hypothyroidism

The 14 symptoms and signs identified by Billewicz et al. were evaluated. Two features, i.e., pulse rate and cold intolerance, had positive and negative predictive values below 70%, and were excluded.

The most sensitive features were delayed ART (77%) and dry skin (76%), while the most specific were slow movements (98.7%) and diminished hearing (97.5%). A positive predictive value was highest for slow movements (96.5%) and puffiness (94.2%). On the other hand, a negative predictive value was highest for ART (80.3%) and dry skin (72.7%).

As women aged > 55 years also complained of “hypothyroid” symptoms, especially constipation and dry skin, an age-correcting factor was added. One point was added to the sum of symptoms and signs in younger women (aged < 55 years).[10]

A score >5 points defined hypothyroidism, while a score of 0-2 points defined euthyroidism. Sixty two percent of all overt hypothyroidism was detected by the new score (as compared to 42% with the Billewicz score).

The new score was higher in overt hypothyroid smokers than in nonsmokers (7.6 ± 3.2 vs. 5.5 ± 2.7; P = 0.024). The score demonstrated excellent correlation with tests of tissue hypothyroidism (r = 0.76 for ART, P < 0.0001; r = 0.060 for total cholesterol, P < 0.00001; r = 0.55 for creatine kinase). Surprisingly, no correlation was observed with serum TSH levels (r = 0.01; P = NS).[10]

The clinical score for tissue hypothyroidism deserves wider usage and attention. It has highlighted the common clinical features of the condition, while emphasizing the changes in presentation that have occurred over the past few decades. The score has underscored the concept of tissue hypothyroidism, given an easy method of assessing its severity. It can be used to evaluate patients with discordant laboratory results, and to monitor effects of therapy.[10]

Another simple questionnaire known as the Thyroid Symptom Questionnaire (TSQ) has been used to detect[11] how patients feel on medication. The TSQ questions are derived from symptoms reported by patients to the British Thyroid Foundation Newsletter.[12] The 12 questions are listed in Table 9.

Table 9

Thyroid symptom questionnaire

In a group of 597 hypothyroid subjects, and 551 euthyroid controls, significant differences were seen in TSQ screening. A total of 35.0% of controls, 46.8% of patients, and 48.6% of euthyroid patients scored ≥ 3 on the TSQ (P < 0.001 for patients vs. controls, and for euthyroid patients vs. controls).

This community-based study showed that the TSQ can be used to assess well- being in hypothyroid patients on thyroxine replacement. A larger number of patients report dissatisfaction while on treatment. A total of 46.8% of all patients had a TSQ ≥ 3, while 37.2% and 25.9% scored ≥ 4 and ≥ 5 respectively. These values were significantly higher than the 35.0%, 24.9%, and 17.6% of controls who scored similar grades on the TSQ.

Symptoms with highest differences between patients and controls were “remembering things” (P = 0.014 all patients vs. controls), “can’t think of the right word” (P = 0.009), “felt tired and lethargic” (P = 0.001). “Able to think clearly” (P = 0.007), and “clumsy, bumped into things and fallen over” (P = 0.034).[11]

THYROID MALIGNANCY

A grading system for ultrasonologically detected thyroid nodules has recently been reported.

The TIRADS (Thyroid Imaging Reporting and Data System) grades thyroid nodules into six categories (TIRADS 2 to 6).[13]

The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 88, 49, 49, 88, and 94% respectively, when compared with fine-needle aspiration biopsy results.

This grading system can be used to avoid unnecessary interventional procedures. TIRADS 2 represents benign findings; TIRADS 3 is probably benign, while TIRADS 4A and 4B represent undetermined and suspicious findings respectively. An imaging picture consistent with malignancy is graded as TIRADS 5, while TIRADS 6 represents confirmed malignancy [Table 10].

Table 10

US characteristics of thyroid nodules, 10 US with their malignancy risk, and TIRADS category

The authors feel that patient management and cost-effectiveness improved with the TIRADS,[13] which has established standard codes to be used in both endocrinology and radiology.

CONCLUSION

This compendium has tried to bring together clinical grading and scoring systems for the diagnosis of goiter, hypothyroidism, hyperthyroidism, and Grave's opthalmoapthy. It highlights the old, as well as relatively modern, methods of clinical diagnosis in thyroidology. The compendium should be useful for medical students and practitioners, as well as physicians and endocrinologists.

The first thyroid score (based on thyroid function tests) was established by Schultz and Ziene in 1956 to predict relapse of thyrotoxic patients after radioactive iodine.[14] The first clinical thyroid score was the index of Crooks, Murray and Wayne, created by trial and error in 1959,[4] which we now know as Wayne's Index. Thyroidology has grown immensely since then. Most of the diagnostic tools and clinical investigations which we use today will not be recognized by those who practised thyroid medicine long ago.

Some things, however, do not change. The need for clinical skills will remain paramount in the assessment and management of thyroid disease, and in fact, all medical conditions. As we complete 55 years of use of the first score in thyroid disease, this is a fitting tribute to the doyens of clinical thyroidology.