Tests Indicate Corticosteroid Regimen for PMR Patients

By Barbara Biedrzycki, RN, MSN, AOCN, CRNP

Summary—Polymylagia rheumatica (PMR) is known for its increased erythrocyte sedimentation rate (ESR), elevated interleukin 6 (IL-6) levels, and dramatic improvement, usually within 72 hours, following a low to moderate dose of corticosteroid. Researchers set out to explore clinical and laboratory data to determine optimal parameters for the dosing and duration of corticosteroid therapy, as there are no current standard practice guidelines for this treatment of choice. Analysis of data revealed three distinct subsets of PMR patients for whom diagnostic variables may predict optimal therapy1 and assist clinicians in determining the most appropriate medication dosage and schedule.

PMR is an inflammatory condition featuring morning stiffness and pain mainly in the shoulder and pelvic girdle area, fever, malaise, and weight loss. It usually presents with a markedly increased ESR, anemia, and elevated interleukin 6 (IL-6) levels. Although muscle weakness is not associated with PMR, people with this illness typically have trouble brushing their hair, getting out of a chair, and getting dressed.1,2

Giant-cell arteritis (GCA), which some believe is associated with PMR as another aspect of a single disease, causes a systemic panarteritis affecting medium and large vessels. Its classic symptoms are headache, scalp tenderness, visual symptoms, jaw claudication, and throat pain.

Similarities between PMR and GCA are:

• The conditions often coexist; about 50% of patients have both.

• Both usually affect those over age 50.

• Both show similar patterns of cytokines in the blood and arteries.

• Both show the same HLA haplotypes.

Differences between PMR and GCA are:

• PMR responds to low-dose corticosteroid therapy, usually 10-20 mg/d, whereas GCA requires a higher dose, usually 40-60 mg/d.

• GCA causes blindness; PMR does not.2

Dramatic improvement, usually within 72 hours, with a low to moderate dose of corticosteroid is considered a possible diagnostic criterion for PMR. Because there are no standard guidelines for the optimal dose or duration of corticosteroid therapy for PMR, researchers explored clinical and laboratory data to determine if parameters could be identified to divide patients into treatment groups with different corticosteroid requirements.1

Study Methodology

Researchers prospectively studied 30 patients diagnosed with PMR who received a specific corticosteroid regimen. Inclusion parameters based on diagnostic criteria of PMR were:

• ESR > 40 mm/h (if diagnosis was independently confirmed by second rheumatologist, exceptions were made to the ESR criterion);

• morning stiffness > 30 minutes;

• and pain in neck/arms, hips/thighs, neck/torso > one month.

The exclusion parameter was histological evidence of GCA. A temporal artery biopsy was performed on those who presented with headache, jaw claudication, scalp tenderness, or abnormal temporal arteries.1

The corticosteroid treatment plan consisted of initial treatment with 20 mg of prednisone every morning. If the patient responded positively, the prednisone was decreased by 2.5 mg every two weeks. If there was no response, prednisone was increased by 10 mg/d before tapering. If the patient experienced a return of active disease after tapering, the prednisone dose was increased by 5 mg/d. After the third flare-up of active disease, the patient was prescribed prednisone at the discretion of the physician. Patients were followed for six months after completion of corticosteroid therapy to assess for disease relapse.1

Study Results

Although 30 patients initially met the diagnostic criteria for inclusion in this study, the final study cohort was 27 because the diagnoses changed for three subjects before the study ended. One person was diagnosed with bladder cancer, and two were diagnosed with rheumatoid arthritis. Analyzing the clinical and laboratory data led researchers to categorize patients with PMR into three distinct subsets. (See table, Major Characteristics of Study Subsets, p. 62.) Comparisons were made initially and at four-week periods of therapy, using a rank sum test for pain scores, ESR, and plasma IL-6 levels.1

Results showed the length of therapy required varied greatly among groups. Four patients completely discontinued corticosteroid therapy after 18 weeks without any relapse. However, 50% of the entire cohort was still receiving corticosteroid therapy after 15 months. One patient continued to require corticosteroid therapy for more than two years.1

Researchers determined that the patients who may benefit most from a short course (less than a year) of low-dose prednisone are those with an initial ESR < 50 mm/h and the IL-6 < 10 pg/ml and who respond promptly without relapses, based on subset A’s profile.

When the initial ESR is > 50 mm/h and the IL-6 > 10 pg/ml, a more challenging disease condition is indicated and the patient may relapse as the prednisone is tapered. In this case, the disease is classified as relapsing (subset B). If the patient does not respond at all to the initial dose of 20 mg/d prednisone, the illness is classified as resistant (subset C). A decrease in IL-6 to less than 10 pg/mg after one month of therapy indicates that the disease will not be resistant to corticosteroid therapy, and a careful titration of the corticosteroid is indicated to prevent relapses.

If the disease is classified as relapsing or resistant, investigators conclude that corticosteroid therapy will be needed most likely for more than a year.

Implications for Practice

This study provides useful information to help clinicians diagnose, treat, and educate patients with PMR. As PMR and GCA may be different presentations of the same disease, advanced practice nurses need to be alert to signs and symptoms of both. Headache, scalp tenderness, visual changes, jaw claudication, throat pain, and tender temporal arteries may indicate the need for a temporal artery biopsy to diagnose GCA.

In addition to the risk for blindness, people with GCA are susceptible to other vascular complications, such as aortic aneurysms.2 Although 28% of subset C subjects developed GCA, the study cohort was too small to state that there is an overall risk for this subgroup to progress to GCA.1

An important consideration in the management of patients with PMR, is the risk for many other health problems that accompany prolonged therapy with corticosteroids. Especially in the population over age 50, where PMR is most prevalent, there is an increased risk of hypertension and osteoporosis.3

There is still much to be learned about PMR, including its pathogenesis and the molecular basis of corticosteroids’ therapeutic action on this disease. Exploring PMR’s relationship to GCA and other rheumatic diseases through clinical and pathogenic research will lead to a better understanding of the disease and its optimal treatment.



Table-Major Characteristics of Study Subjects

Subset A, n=8 (30%)
     • Short term disease
     • Rapid response to initial prednisone 20 mg/d
     • Treatment tapered without relapses
     • Treatment time < 1 year
     • Long-term remission
     • Initial erythrocyte sedimentation rate (ESR) < 50 mm/h
     • Initial and four weeks after therapy IL-6 < 10 pg/ml
     • Median pain score 6.7 (scale 0-10)*
Subset B, n=12 (44%)
     • Relapsing disease
     • Initial response to prednisone 20 mg/d
     • Relapse with pain and stiffness on tapering of prednisone to < 7.5 mg/d
     • Treatment time > 1 year
     • Initial ESR > 50 mm/h
     • Initial IL-6 > 10 pg/ml, decreased after one month of therapy IL-6 <10 pg/ml
     • Median pain score 7.1
Subset C, n=7 (26%)
     • Resistant disease
     • Partial response to prednisone 20 mg/d
     • Increased prednisone dose to 30 mg/d or 20 mg/d > 4 weeks
     • Treatment > 1 year
     • Initial ESR > 50 mm/h
     • Initial and four weeks after therapy IL-6 > 10 pg/ml
     • Median pain score 8.4*
     • Two patients (29%) developed giant cell arteritis
* Differences statistically significant at P=0.5 level.
Source: Weyland CM, Fulbright JW, Evans JM, et al. Corticosteroid requirements in polymyalgia rheumatica. Arch Intern Med 1999;159:577-584.


References

1. Weyland CM, Fulbright JW, Evans JM, et al. Cortico steroid requirements in polymyalgia rheumatica. Arch Intern Med 1999;159:577-584.

2. Hellmann DB, Stone JH. Arthritis and Musculoskel etal Disorders. In: Tierney LM, McPhee SJ, Papadakis MA, eds. Current Medical Diagnosis and Treatment 1999. Stanford, CT: Appleton and Lange; 1999:786-837.

3. Spratto GR, Woods AL. PDR Nurse’s Handbook. Montvale, NJ: Medical Economics Co. 1999:110-118.