Real-world effectiveness of anti-interleukin-23 antibodies in chronic plaque-type psoriasis of patients from the Austrian Psoriasis Registry (PsoRA)

With the introduction of the latest class of biologic drugs targeting interleukin (IL)-23p19, three new, highly effective drugs can be used for the treatment of chronic plaque psoriasis. However, poorer skin improvement as well as higher rates of serious adverse events have been reported for patients under real-world conditions (outside clinical trials). This accounts especially for patients who have already been treated with biologic drugs. We therefore aimed to determine effectiveness and safety of IL-23p19 inhibitors in real-world patients by analysing data from the Psoriasis Registry Austria (PsoRA) in this observational, retrospective, multicentre cohort study. Data for 197 patients (52.3% biologic-non-naïve), who were treated with anti-IL-23p19 antibodies (127 guselkumab, 55 risankizumab and 15 tildrakizumab) for at least 3 months, were eligible for analysis. In general, biologic-non-naïve patients displayed a less favourable response to anti-IL-23 treatment as compared to biologic-naïve patients. However, after correction for previous biologic exposure, few differences in PASI improvement were detected among biologic-naïve and -non-naïve patients treated with different IL-23p19 inhibitors. This indicates that treatment effectiveness is not related to the class of the previously administered therapy in biologic-non-naïve patients. Therefore, IL-23p19 inhibitors represent a promising treatment alternative for patients who have not responded to previous biologics. However, as with other biologic agents (including IL-17 inhibitors), we did not observe an entirely satisfactory treatment response (i.e. PASI < 3 and/or PASI 75) to anti-IL-23 treatment in one out of four to five patients. Adverse events (mainly non-severe infections) were observed in 23 (11.7%) patients with no major differences regarding the administered IL-23 inhibitor or previous biologic exposure.

Pruritus Intensity Scales across Europe: a prospective validation study

BACKGROUND

Chronic pruritus (CP) is a subjective symptom, and it is necessary to assess its intensity with validated patient-reported outcome tools in order to allow determination of the treatment course.

OBJECTIVES

So far, the itch intensity scales were validated in small cohorts and in single languages. Here, we report the validation of the numerical rating scale, the verbal rating scale and the visual analogue scale for the worst and average pruritus intensity in the last 24h in several languages across Europe and across different pruritic dermatoses.

METHODS

After professional translation, the intensity scales were digitized for use as a tablet computer application. Validation was performed in clinics for Dermatology in Austria, France, Germany, Italy, Poland, Russia, Spain, Switzerland and Turkey.

RESULTS

A total of 547 patients with contact dermatitis, chronic nodular prurigo, psoriasis vulgaris, lichen planus or cutaneous T-cell lymphoma were included. The intensity scales showed a high level of reproducibility and inter-correlations with each other. The correlation with the Dermatology Life Quality Index was weak to strong in nearly all countries and dermatoses with the exception of France and patients with chronic nodular prurigo, for which no statistically significant correlations were found.

CONCLUSIONS

The numerical rating scale, the verbal rating scale und the visual analogue scales are valid instruments with good reproducibility and internal consistency in German (Germany, Austria, Switzerland), French, Italian, Polish, Russian, Spanish and Turkish for different pruritic dermatoses. VAS worst was the best reproducible and consistent measuring instrument in all countries.

Biologic drug survival rates in the era of anti-interleukin-17 antibodies: a time-period-adjusted registry analysis

Background

Drug survival rates reflect efficacy and safety and may be influenced by the availability of alternative treatment options. Little is known about time‐dependent drug survival in psoriasis and the effect of increasing numbers of biologic treatment options.

Objectives

To determine whether drug survival is influenced by the availability of treatment options and by factors such as gender, psoriatic arthritis or previous biologic treatment.

Methods

This observational, retrospective, multicentre cohort study analysed data from patients registered in the Austrian Psoriasis Registry (PsoRA) who were treated with biologics between 1 January 2015 and 30 November 2019.

Results

A total of 1572 patients who received 1848 treatment cycles were included in this analysis. The highest long‐term Psoriasis Area and Severity Index improvement was observed after treatment with ixekizumab, followed by ustekinumab and secukinumab, adalimumab and etanercept. Overall, ustekinumab surpassed all other biologics in drug survival up to 48 months. However, when adjusted for biologic naïvety, its superiority vanished and drug survival rates were similar for ixekizumab (91·6%), secukinumab (90·2%) and ustekinumab (92·8%), all of them superior to adalimumab (76·5%) and etanercept (71·9%) at 12 months and beyond. Besides biologic non‐naïvety (2·10, P < 0·001), the introduction of a new drug such as secukinumab or ixekizumab (relative hazard ratio 1·6, P = 0·001) and female gender (1·50, P = 0·019) increased the risk of treatment discontinuation overall, whereas psoriatic arthritis did not (1·12, P = 0·21).

Conclusions

The time‐dependent availability of drugs should be considered when analysing and comparing drug survival. Previous biologic exposure significantly influences drug survival. Women are more likely to stop treatment.

What is already known about this topic?

Female gender and previous biologic exposure have been discussed as predictors for decreased drug survival in patients with psoriasis, but it remains unknown whether a time‐dependent increased availability of treatment options alters biologic drug survival.

What does this study add?

The increased availability of alternative biologic treatments over time leads to an elevated risk for treatment discontinuation overall; therefore, drug survival analysis has to be time adjusted.

Moreover, the study reveals that the impact of previous biologic treatment on drug survival is tremendous and confirms worse drug survival in female patients.

Linked Comment: Gniadecki. Br J Dermatol 2021; 184:996–997.

Cross-European validation of the ItchyQoL in pruritic dermatoses

BACKGROUND

Chronic pruritus (CP) is a frequently occurring symptom in inflammatory dermatoses, causing a high burden and limitations to health-related quality of life (HRQoL).

OBJECTIVE

The ItchyQoL was developed to assess the impairment to HRQoL in patients with CP. However, it has only been validated in English and German. Here, we report the validation in several languages across Europe.

METHODS

After professional translation, the versions of ItchyQoL were digitized for use as a tablet application. Validation was performed in clinics for dermatology in Austria, France, Germany, Italy, Poland, Russia, Spain, Switzerland and Turkey.

RESULTS

Five hundred and thirty-five patients with either contact dermatitis, chronic prurigo - nodular type, psoriasis vulgaris, lichen planus or mycosis fungoides/Sézary syndrome and with CP ≥ 3 on the numerical rating scale were included. ItchyQoL showed a high level of consistency (Cronbach's-α, all: 0.95) and test-retest reliability (intraclass correlation: 0.91). It strongly correlated with the Dermatology Life Quality Index (r = 0.72, P < 0.001) and moderately correlated with itch intensity scales in the study population (visual analogue scale r = 0.46; numerical rating scale r = 0.51; verbal rating scale r = 0.51, for all: P < 0.001).

CONCLUSION

ItchyQoL is now also validated in French, Italian, Polish, Russian, Spanish and Turkish and can be used in clinical trials in countries speaking these languages.

An update on the diagnosis and management of psoriatic arthritis

Psoriasis is a common inflammatory disease with complex genetic background affecting approximately 2-3% of the population in the Western hemisphere. Around 20% of psoriasis patients also suffer from psoriatic arthritis (PsA). The clinical spectrum comprises a wide variety of arthritic manifestations ranging from dactylitis, peripheral symmetric or asymmetric mono-, oligo-, and polyarticular arthritis, spinal disease and enthesitis. As psoriasis precedes PsA in 75-80% of affected patients, dermatologists might play a pivotal role in early diagnosis of the disease. Furthermore, magnetic resonance imaging (MRI) scanning and ultrasonography have improved the radiological diagnosis of peripheral PsA, psoriatic spondylarthropathy and enthesitis. Besides the traditional treatment of PsA the introduction of biologics has led to a significant improvement in the treatment of the disease. To further improve diagnosis, treatment and quality of life in our patients suffering from PsA an excellent interdisciplinary collaboration between dermatologists, radiologists and rheumatologists is a necessity of utmost importance.

In vivo reflectance confocal microscopy: automated diagnostic image analysis of melanocytic skin tumours

BACKGROUND

In vivo reflectance confocal microscopy (RCM) has been shown to be a valuable imaging tool in the diagnosis of melanocytic skin tumours. However, diagnostic image analysis performed by automated systems is to date quite rare.

OBJECTIVES

In this study, we investigated the applicability of an automated image analysis system using a machine learning algorithm on diagnostic discrimination of benign and malignant melanocytic skin tumours in RCM.

METHODS

Overall, 16,269 RCM tumour images were evaluated. Image analysis was based on features of the wavelet transform. A learning set of 6147 images was used to establish a classification tree algorithm and an independent test set of 10, 122 images was applied to validate the tree model (grouping method 1). Additionally, randomly generated 'new' learning and test sets, tumour images only and different skin layers were evaluated (grouping method 2, 3 and 4).

RESULTS

  The classification tree analysis correctly classified 93.60% of the melanoma and 90.40% of the nevi images of the learning set. When the classification tree was applied to the independent test set 46.71 ± 19.97% (range 7.81-83.87%) of the tumour images in benign melanocytic skin lesions were classified as 'malignant', in contrast to 55.68 ± 14.58% (range 30.65-83.59%; t-test: P < 0.036) in malignant melanocytic skin lesions (grouping method 1). Further investigations could not improve the results significantly (grouping method 2, 3 and 4).

CONCLUSIONS

The automated RCM image analysis procedure holds promise for further investigations. However, to date our system cannot be applied to routine skin tumour screening.

Confocal laser scanning microscopy-guided surgery for neurofibroma

The neurofibromatoses comprise at least two separate genetic disorders with variable clinical features and an unpredictable course. The most common type, neurofibromatosis 1, is characterized by > or = 6 café-au-lait spots and the occurrence of neurofibromas, which may present as cutaneous, subcutaneous or plexiform lesions. Normally, excision of neurofibromas is only indicated in the presence of neurological symptoms, suspicion of malignancy or for exceptional cosmetic reasons. For a good functional and aesthetic result with the least danger of recurrence, the surgeon's goal is to excise as much tissue as necessary and as little tissue as possible. One of the main issues during the surgical procedure is to distinguish between neurofibroma and surrounding tissue. We report for the first time the use of confocal laser scanning microscopy to differentiate between neurofibroma and healthy skin.

Tinea capitis in early infancy treated with itraconazole: a pilot study

BACKGROUND

Tinea capitis is the most common fungal infection of the scalp in childhood, but a very rare disorder in the first year of life.

OBJECTIVE

To evaluate the efficacy, tolerability and safety of itraconazole in 7 children aged between 3 and 46 weeks (median: 36 weeks) suffering from tinea capitis caused by Microsporum canis.

METHODS

Prospective case note study. In all patients KOH testing and fungal cultivation on Sabouraud dextrose agar were performed.

RESULTS

7 patients (5 girls and 2 boys) were included in the period between 2001 and 2008. The causative etiologic agent was Microsporum canis in all children. The patients received itraconazole 5mg/kg bodyweight daily for 3 to 6 weeks with no clinically side effects being noted. In all patients clinical and mycological cure could be achieved.

CONCLUSION

Itraconazole proved to be a safe and effective treatment option for Microsporum canis induced tinea capitis in children in their first year of life.

In vivo confocal laser scanning microscopy of melanocytic skin tumours: diagnostic applicability using unselected tumour images

BACKGROUND

In vivo confocal laser scanning microscopy (CLSM) represents a novel imaging tool that allows the noninvasive examination of skin cancer morphology in real time at a 'quasi-histopathological' resolution viewing microanatomical structures and individual cells.

OBJECTIVES

To validate diagnostic confocal examination of melanocytic skin tumours using unselected tumour images.

METHODS

In the present study, we used a total of 3709 unselected CLSM tumour images obtained from 20 malignant melanomas and 50 benign naevi. The entire set of images derived from each tumour was evaluated by independent observers. Classification tree analysis based on a subsample of 857 tumour images was performed to develop a diagnostic algorithm.

RESULTS

Overall, sensitivity and specificity of 97.5% and 99% could be achieved by the independent observers (positive predictive value 97.5%, negative predictive value 99%). Classification tree analysis yielded a three-step algorithm based on only three morphological CLSM features, facilitating a correct classification in 92.4% of the benign naevus images and 97.6% of melanoma images.

CONCLUSIONS

In vivo CLSM augurs a sea change in the way we will view skin tumour processes clinically at the bedside and merits application for use as a screening tool in skin oncology.

Delayed-type hypersensitivity to low molecular weight heparins and heparinoids: cross-reactivity does not depend on molecular weight

BACKGROUND

Cross-reactivity is a widespread phenomenon in patients who develop cutaneous delayed-type hypersensitivity (DTH) reactions to low molecular weight heparins (LMWHs). As molecular weight is believed to be a key determinant of sensitization to heparins, the recently developed LMWH bemiparin, with the lowest molecular weight of all LMWHs, appeared to be a significant improvement.

OBJECTIVES

To evaluate cross-reactivity between bemiparin and several other LMWHs and heparinoids by means of subcutaneous testing. Methods Test doses of bemiparin and several other LMWHs/heparinoids were given to eight patients with a history of local eczematous reactions after subcutaneous injection of enoxaparin.

RESULTS

Seven of eight patients showed cross-reactivity following subcutaneous injection of bemiparin. In addition, nearly all tested substances caused local eczematous reactions in at least some patients, with the exception of fondaparinux, which was well tolerated by all patients. Of all substances tested, bemiparin had the highest cross-reactivity with enoxaparin. Substances with a lower molecular weight did not cross-react less frequently than the others.

CONCLUSIONS

No significant correlation was found between the molecular weight of the tested substances and the frequency of DTH reactions. In patients with DTH to enoxaparin, the LMWH bemiparin is not a suitable alternative.

The use of confocal laser-scanning microscopy in microsurgery for invasive squamous cell carcinoma

BACKGROUND

Ex-vivo confocal laser-scanning microscopy offers rapid imaging of excised tissue specimens without conventional histotechnical procedures. As vertical sections are prepared, morphological features can be assessed according to standard criteria used in conventional histopathology.

OBJECTIVES

To validate the diagnostic confocal examination of squamous cell carcinoma (SCC) in microscopy-guided surgery.

METHODS

Four independent observers received standardized instructions about diagnostic confocal microscopy features of SCC. Subsequently, 120 confocal images of fresh excisions from SCC or normal skin, imaged using a commercially available, near-infrared, reflectance confocal laser-scanning microscope, were evaluated by each observer.

RESULTS

General morphology, such as location, size and shape of the cancer area could be visualized by the imaging system. Furthermore, densely packed and irregularly organized nuclei and nuclear atypia could be delineated. Overall, a sensitivity of 95% and a specificity of 96.25% were achieved by the four observers (positive predictive value 96.25%, negative predictive value 95.23%).

CONCLUSIONS

This study provides a set of well-described morphological criteria with obvious diagnostic impact which should be used in further investigations. In the future, confocal laser-scanning microscopy may guide microsurgery of any skin cancer.

A 5-year (2000?2004) epidemiological survey of Candida and non-Candida yeast species causing vulvovaginal candidiasis in Graz, Austria

Vulvovaginal candidasis (VVC) is a common disease. The majority of cases is caused by Candida albicans, but in recent years an increase has been observed in the frequency of non-albicans Candida infections, especially due to C. glabrata and C. tropicalis. The aim of the study was to assess the prevalence of non-albicans Candida infections in patients suffering from VVC. Therefore, the statistical data of culture-confirmed VVC ascertained at the Institute of Hygiene (Medical University Graz) have been studied. Altogether, 10,463 samples from patients with vulvovaginal complaints were analysed in the years 2000-2004, a number of 3184 proved to be culture-positive for yeast. Candida albicans was the most prevalent cause in 87.9% of all cases. Non-albicans Candida yeast were detected in 12.1%, mainly C. glabrata and Saccharomyces cerevisiae. During a 1-year period 185 patients showed more than one episode of VVC. Patients aged 21-40 years were significantly more prone to suffer from VVC compared with other age-related groups.

Role of microchimerism in the pathogenesis of oral lichen planus

OBJECTIVE

Microchimerism of persistent fetal cells has been implicated in some cell-mediated autoimmune diseases. This study examines the hypothesis that fetal microchimerism plays a role in the pathogenesis of lichen planus (LP) affecting the oral cavity.

STUDY DESIGN

Mucosal biopsies of 12 women with oral LP (OLP) were tested for the presence of both male cells and male DNA originating from prior pregnancies or prior blood transfusions. Six male patients with OLP served as a control group. Biopsies were analyzed for the presence of Y-chromosome-positive cells by fluorescence in situ hybridization (FISH) with X- and Y-specific DNA probes. To confirm the FISH findings, we used fluorescent polymerase chain reaction (PCR) to identify Y-chromosome sequences in DNA extracted from mucosal lesions.

RESULTS

Using FISH technology, all the 18 biopsy samples showed good hybridization results. In females, Y-chromosome-specific signals were not detected by FISH at any site of the lesions. PCR amplification demonstrated a single peak at the locus specific for the X-chromosome.

CONCLUSION

Male DNA microchimerism was not present in any of the investigated lesions, suggesting that microchimerism because of persisting male fetal cells is unlikely to play a major role in the pathogenesis of OLP.

Search for occult secondary osteoporosis: impact of identified possible risk factors on bone mineral density

OBJECTIVES

To determine whether the use of more elaborate diagnostic tests can identify possible risk factors for secondary osteoporosis and to evaluate the impact of these possible risk factors on the severity of bone disease in the study population.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

We have investigated 377 subjects (285 females, 92 males) with osteoporosis (T-score less than -2.5 in dual energy X-ray absorption) or nontraumatic lumbar vertebral fractures; these patients were referred to our hospital, a secondary care centre, for evaluation and treatment of osteoporosis.

RESULTS

Osteoporosis without attributable risk factor was diagnosed in 106 women (37%) and 30 men (33%). In 241 patients (179 women, 62 men) one or more possible risk factors for osteoporosis (in this paper also called subclinical disease) were revealed. The most common were lactose malabsorption, disturbed exocrine pancreatic function and renal tubular disturbances, including renal hypercalciuria, incomplete renal tubular acidosis and mild phosphate diabetes. The number of possible risk factors in the individual patient was significantly related to the severity of osteoporosis as assessed by Z-scores (Spearman correlation r = -0.43, P < 0.001, n = 172 for females; r = -0.28, P < 0.05, n = 65 for males).

CONCLUSIONS

All the identified subclinical diseases would have remained undetected if the currently accepted guidelines for the investigation of patients with osteoporosis were applied. The statistically significant correlation between the number of identified possible risk factors and the severity of bone disease in the individual patient strongly suggests the pathogenetic significance of the identified subclinical diseases. It is yet to be shown, whether specific treatment of these subclinical diseases yields additional improvement of bone mass as compared with standard treatment of osteoporosis.

Granulomatous cheilitis and Borrelia burgdorferi: polymerase chain reaction and serologic studies in a retrospective case series of 12 patients

BACKGROUND

Granulomatous cheilitis (GC) is a chronic granulomatous inflammation of the lips of unknown etiology, which may be associated with peripheral facial nerve paralysis and/or lingua plicata (Melkersson-Rosenthal syndrome [MRS]). Borrelia burgdorferi is a spirochete that causes Lyme borreliosis, a multisystemic infectious disease with frequent occurrence of facial nerve paralysis. An etiologic role of B burgdorferi in various granulomatous diseases has been suggested. The present study was performed to examine a possible causative role of B burgdorferi for GC/MRS by B burgdorferi-specific polymerase chain reaction analysis of biopsy specimens from affected lip tissue and determination of B burgdorferi IgG and IgM serum antibodies using enzyme-linked immunosorbent assay and immunoblot tests.

OBSERVATIONS

We examined a retrospective case series of 12 patients with GC/MRS from a Lyme borreliosis endemic area (median duration of disease, 8 months [range, 3-348 months]). Borrelia burgdorferi-specific DNA could not be amplified by polymerase chain reaction in any of the 12 patients. One (13%) of 8 patients tested had a serum B burgdorferi IgG response on enzyme-linked immunosorbent assay, and 2 patients (25%) had an IgM response, but immunoblot testing yielded negative results in all 8 patients.

CONCLUSION

The results of the present study do not indicate that B burgdorferi has an etiologic role in GC/MRS.

Prevalence and characterization of renal tubular acidosis in patients with osteopenia and osteoporosis and in non-porotic controls

BACKGROUND

Chronic metabolic acidosis may increase alkali mobilization from the bone and thus promote the development of osteoporosis. The objective of the current study was to compare urinary acidification in patients with reduced bone mineral content with that in control subjects with normal bone density.

METHODS

Forty-six subjects (41 females, 5 males) with osteopenia or osteoporosis were studied. In none of the subjects were overt metabolic acidosis, derangement of potassium homeostasis, or renal insufficiency present. Distal tubular acidification was studied by means of oral ammonium chloride loading test (0.1 g/kg body weight) and the oral frusemide test (40 mg). In addition the frusemide test was performed in 20 healthy age- and sex-matched controls (17 females, 3 males).

RESULTS

In all control subjects a urinary pH <5. 5 was observed following the ingestion of 40 mg frusemide. In contrast, in patients with reduced bone mineral density incomplete renal tubular acidosis type I (RTA I) was diagnosed in 10 of 46 subjects (22%) by oral ammonium chloride loading test. Disorders possibly related to RTA I were detected in eight of these 10 patients. Thirty-six patients had a normal urinary pH response following oral ammonium chloride loading. Oral frusemide, 40 mg, failed to lower urinary pH <5.5 in sixteen patients (35%), these included 10 subjects with incomplete RTA I, and six subjects with a normal oral ammonium chloride loading test. An abnormal frusemide test was found in 35% of patients with reduced bone mass and in none of the normal controls (chi(2)=7.39; P<0.01). With the ammonium chloride test as the gold standard for diagnosis of distal RTA, the frusemide test showed a sensitivity of 1.0 (95% CI, 0.69-1.0) and a specificity of 0.89 (95% CI, 0.78-0.96) for the diagnosis of distal RTA. Patients with incomplete RTA I were younger than those without incomplete RTA I (42+/-16 vs 54+/-14 years; P=0.025; mean+/-SD). Basal serum bicarbonate concentrations and capillary pH did not differ between the groups.

CONCLUSION

Incomplete RTA I may be prevalent in a significant proportion of patients suffering from osteopenia or osteoporosis. The outcome of the frusemide test suggests either a defect of the H(+)ATPase in the cortical collecting tubule (CCT) or a defective Na(+) reabsorption in the CCT. Prospective studies are needed to further elucidate the impact of incomplete RTA I on the development of reduced bone mineral content.

Incomplete renal tubular acidosis in 'primary' osteoporosis

Chronic metabolic acidosis may increase alkali mobilization from bone and thus promote the development of osteoporosis. While it is undisputed that overt metabolic acidosis is associated with metabolic bone disease, renal acidification in patients with idiopathic osteoporosis has not been studied systematically. The purpose of this study was to investigate the prevalence of renal acidification defects in patients with 'primary' osteoporosis. Thirty-two women (including 10 premenopausal women) and 16 men who were referred to our department for investigation of osteoporosis were enrolled in this study. Patients with obvious or possible secondary osteoporosis were excluded. None of the patients had overt metabolic acidosis. In random urine samples 12 of the 48 patients had pH levels below 5.5 and were therefore considered to have normal renal acidification. The remaining 36 patients underwent further testing by a short-course oral ammonium chloride load. In this test nine of these 36 patients (7 men and 2 premenopausal women) failed to lower urinary pH below 5.5 despite the induction of systemic metabolic acidosis. In these patients, therefore, the diagnosis of incomplete distal renal tubular acidosis was made (RTA I). Patients with incomplete RTA I had significantly lower spontaneous plasma pH (7.38 +/- 0.0081 vs 7.41 +/- 0.004, mean +/- SEM, p = 0.002), a lower serum bicarbonate concentration (21.9 +/- 0.49 mmol/l vs 23.1 +/- 0.24 mmol/l, p = 0.034), a lower base excess (-2.33 +/- 0.42 mmol/l vs -0.55 +/- 0.21 mmol/l, p = 0.001) and lower Z-scores in bone densitometry (-2.18 +/- 0.27 vs -1.40 +/- 0.15, p = 0.028) than patients with normal renal acidification. In conclusion, a high prevalence of incomplete RTA I (in 44% of the male patients, 20% of the premenopausal female patients and 6% of all female patients) was found in patients with osteoporosis who, without testing, would have been diagnosed as having 'primary' osteoporosis. The mild metabolic acidosis observed in these patients may have contributed to loss of bone mass by a compensatory mobilization of alkali and calcium from bone. Because of possible therapeutic consequences (e.g., administration of alkali salts and high doses of vitamin D) we propose that measurements of urinary pH and, if necessary, ammonium chloride testing should be included in the diagnostic investigation especially of male and of premenopausal female patients with osteoporosis. Since referral bias, although unlikely, cannot be excluded in our study, the prevalence of RTA I in unselected patients with osteoporosis needs to be determined at primary screening institutions.