Achilles tendon rupture and its association with fluoroquinolone antibiotics and other potential risk factors in a managed care population

Early steps in the development of a claims-based targeted healthcare safety monitoring system and application to three empirical examples

BACKGROUND

Several efforts are under way to develop and test methods for prospective drug safety monitoring using large, electronic claims databases. Prospective monitoring systems must incorporate signalling algorithms and techniques to mitigate confounding in order to minimize false positive and false negative signals due to chance and bias.

OBJECTIVE

The aim of the study was to describe a prototypical targeted active safety monitoring system and apply the framework to three empirical examples.

METHODS

We performed sequential, targeted safety monitoring in three known drug/adverse event (AE) pairs: (i) paroxetine/upper gastrointestinal (UGI) bleed; (ii) lisinopril/angioedema; (iii) ciprofloxacin/Achilles tendon rupture (ATR). Data on new users of the drugs of interest were extracted from the HealthCore Integrated Research Database. New users were matched by propensity score to new users of comparator drugs in each example. Analyses were conducted sequentially to emulate prospective monitoring. Two signalling rules--a maximum sequential probability ratio test and an effect estimate-based approach--were applied to sequential, matched cohorts to identify signals within the system.

RESULTS

Signals were identified for all three examples: paroxetine/UGI bleed in the seventh monitoring cycle, within 2 calendar years of sequential data; lisinopril/angioedema in the second cycle, within the first monitoring year; ciprofloxacin/ATR in the tenth cycle, within the fifth year.

CONCLUSION

In this proof of concept, our targeted, active monitoring system provides an alternative to systems currently in the literature. Our system employs a sequential, propensity score-matched framework and signalling rules for prospective drug safety monitoring and identified signals for all three adverse drug reactions evaluated.

Adverse effects of antimicrobials via predictable or idiosyncratic inhibition of host mitochondrial components

This minireview explores mitochondria as a site for antibiotic-host interactions that lead to pathophysiologic responses manifested as nonantibacterial side effects. Mitochondrion-based side effects are possibly related to the notion that these organelles are archaic bacterial ancestors or commandeered remnants that have co-evolved in eukaryotic cells; thus, this minireview focuses on mitochondrial damage that may be analogous to the antibacterial effects of the drugs. Special attention is devoted to aminoglycosides, chloramphenicol, and fluoroquinolones and their respective single side effects related to mitochondrial disturbances. Linezolid/oxazolidinone multisystemic toxicity is also discussed. Aminoglycosides and oxazolidinones are inhibitors of bacterial ribosomes, and some of their side effects appear to be based on direct inhibition of mitochondrial ribosomes. Chloramphenicol and fluoroquinolones target bacterial ribosomes and gyrases/topoisomerases, respectively, both of which are present in mitochondria. However, the side effects of chloramphenicol and the fluoroquinolones appear to be based on idiosyncratic damage to host mitochondria. Nonetheless, it appears that mitochondrion-associated side effects are a potential aspect of antibiotics whose targets are shared by prokaryotes and mitochondria-an important consideration for future drug design.

Open repair of the acutely torn Achilles tendon under local anaesthetic

BACKGROUND

Where surgery has been preferred, the torn Achilles tendon (AT) has most commonly been repaired under general or spinal anaesthetic (GA). Repair using local anaesthetic (LA) has been reported, but does not appear to be widely used.

METHODS

We retrospectively reviewed 87 patients, following open repair using either GA or LA at Nelson Hospital, 2001–2005. Calf strength and ankle range of motion (ROM) were assessed. Subjective pain and function were assessed using the American Academy of Orthopaedic Surgeons Foot and Ankle Questionnaire. Complications, time off work and sport, time in theatre, and hospital were recorded.

RESULTS

Fifty-nine tendons were repaired under GA (68%) and 28 under LA (32%). Outcomes were similar for each group. There was no significant difference in strength and ROM. Foot and Ankle Questionnaire scores were similar. Total theatre time averaged 57 min for GA and 37 min for LA (P = 0.01). LA repairs (82%) were performed as a day case compared with 10% of the GA repairs (P = 0.01). LA patients had a quicker return to work. GA complications included two deep vein thromboses and two pulmonary emboli. One patient from each group had a re-rupture.

CONCLUSION

A repair of the acutely ruptured AT under LA is at least as effective as repair under GA with regard to function, long-term pain and patient satisfaction. LA repair results in significant cost savings due to less theatre time, fewer anaesthetic costs, and a shorter hospital stay.

Operative versus nonoperative treatment for acute Achilles tendon rupture: a meta-analysis based on current evidence

PURPOSE

The aim of this study was to evaluate, in a meta-analysis, the clinical effectiveness of operative treatment for acute Achilles tendon rupture (AATR) compared with nonoperative treatment.

METHODS

We systematically searched six electronic databases (Medline, Embase, Clinical Ovid, BIOSIS and Cochrane registry of controlled clinical trials) to identify randomised controlled trials (RCTs) in which operative treatment was compared with nonoperative treatment for AATR from 1980 to 2011. Trial quality was assessed using the modified Jadad scale. The data was using fixed-effects and random-effects models with mean differences and risk ratios for continuous and dichotomous variables, respectively.

RESULTS

Ten RCTs with a total of 894 patients were screened. The results showed that operative was superior to nonoperative treatment regarding lower risk of re-rupture (P = 0.002) and shorter time for sick leave (P = 0.009) but inferior to nonoperative treatment regarding complication risks (P = 0.004). No significant difference was identified between the two methods regarding the number of patients who successfully returned to pre-injury sports (P = 0.30). Subgroup analyses revealed significant differences in relation to scar adhesion (P < 0.00001), superficial infection (P = 0.05), and sensibility disturbance (P = 0.0003). However, no significant differences were found between the two interventions in relation to deep infection (P = 0.22), deep vein thrombosis (DVT) (P = 0.14), and extreme Achilles tendon lengthening (P = 0.31). Little consensus was obtained in the functional recovery from current trials as a result of an inconsistent assessment system.

CONCLUSIONS

Compared with conservative treatment, operative treatment can effectively reduce the risk of re-rupture but increase the probability of complications. The increased complication risk may be associated with open repair surgery. However, no sufficient evidence is available from current studies to support the belief that operation may lead to better functional recovery.

Performance of a semi-automated approach for risk estimation using a common data model for longitudinal healthcare databases

Different structures and coding schemes may limit rapid evaluation of a large pool of potential drug safety signals using multiple longitudinal healthcare databases. To overcome this restriction, a semi-automated approach utilising common data model (CDM) and robust pharmacoepidemiologic methods was developed; however, its performance needed to be evaluated. Twenty-three established drug-safety associations from publications were reproduced in a healthcare claims database and four of these were also repeated in electronic health records. Concordance and discrepancy of pairwise estimates were assessed between the results derived from the publication and results from this approach. For all 27 pairs, an observed agreement between the published results and the results from the semi-automated approach was greater than 85% and Kappa coefficient was 0.61, 95% CI: 0.19-1.00. Ln(IRR) differed by less than 50% for 13/27 pairs, and the IRR varied less than 2-fold for 19/27 pairs. Reproducibility based on the intra-class correlation coefficient was 0.54. Most covariates (>90%) in the publications were available for inclusion in the models. Once the study populations and inclusion/exclusion criteria were obtained from the literature, the analysis was able to be completed in 2-8 h. The semi-automated methodology using a CDM produced consistent risk estimates compared to the published findings for most selected drug-outcome associations, regardless of original study designs, databases, medications and outcomes. Further assessment of this approach is useful to understand its roles, strengths and limitations in rapidly evaluating safety signals.

Interleukins 4 and 13 modulate gene expression and promote proliferation of primary human tenocytes

Background

Tendon disorders (tendinopathies) pose serious biomedical and socioeconomic problems. Despite diverse treatment approaches, the best treatment strategy remains unclear. Surgery remains the last resort because of the associated morbidity and inconsistent outcomes. We hypothesized that, similar to fibroblasts in various organs, tendon fibroblasts (tenocytes) might be responsive to stimulation with interleukins (ILs), particularly IL-4 and IL-13. These two cytokines share sequence homology, receptor chains and functional effects, including stimulation of fibrogenesis. It is unknown whether tenocytes are responsive to stimulation with IL-4 or IL-13. If true, local use of these cytokines might be used to facilitate tendon repair in patients with tendinopathies or used for tendon tissue-engineering approaches to facilitate tenocyte growth on scaffolds in culture.

Results

Tendon tissues that would normally be discarded were obtained during reconstructive surgery procedures performed for clinical indications. Primary tenocytes were derived from Achilles, posterior tibial, flexor digitorum longus and flexor hallucis longus tendon tissue samples. Reverse transcriptase quantitative PCR (RT-qPCR) experiments revealed that mRNAs for the receptor (R) chains IL-4Rα, IL-13Rα1 and IL-13Rα2, but not the common γ-chain were present in all tested tendon tissues and in cultured tenocytes. Levels of IL-13R chain mRNAs were significantly higher than those of IL-4R mRNA. The cultures responded, in a dose-dependent fashion, to stimulation with recombinant human IL-4 or IL-13, by increasing proliferation rates 1.5 to 2.0-fold. The mRNA levels of 84 genes related to cell cycle regulation were measured by RT-qPCR after 6 h and 24 h of activation. The expression levels of several genes, notably CDK6 and CDKN2B changed more than twofold. In contrast to their effects on proliferation, stimulation with IL-4 or IL-13 had little if any effect on the levels of collagen mRNA or protein in cultured primary tenocytes. The mRNA levels of 84 other genes related to extracellular matrix and cell adhesion were also measured by RT-qPCR; expression of only five genes was consistently changed.

Conclusions

Stimulation with IL-4 or IL-13 could be used to facilitate tendon repair in vivo or to aid in tendon tissue engineering, through stimulation of tenocyte proliferation.

Levofloxacin-induced Achilles tendinitis in a young adult in the absence of predisposing conditions

Fluoroquinolones (FQs) represent a major class of antimicrobials that have a high potential as therapeutic agents. Although FQs are generally safe for the use as antimicrobials, they may induce tendinopathic complications such as tendinitis and tendon rupture. A number of factors have been suggested to further predispose a patient to such injuries. Hitherto, a few published cases on tendon disorders have implicated levofloxacin, a more recently introduced FQ. Here, we report a patient with levofloxacin-induced Achilles tendinitis, who exhibited no known predisposing factors. A 20-year-old man without any history of disease or medication presented with community-acquired pneumonia. Levofloxacin was administered and 3 days later, he complained of pain in the left Achilles tendon and revealed redness and swelling in the area. On suspecting Achilles tendinitis, levofloxacin treatment was discontinued, and the tendinitis subsequently improved. To our knowledge, this is the first case report on FQ-induced Achilles tendinitis in Korea.

A Review of Levofloxacin for the Treatment of Bacterial Infections

Completing its initial phases of drug development in the mid 1990s as the one of the first fluoroquinolones that could be used with confidence to treat respiratory tract infections, levofloxacin went on to become one of the most widely prescribed antibiotics in the world. Available in both oral (po) and intravenous (IV) formulations and with characteristics of over 90% bioavailability, distribution into both extracellular and intracellular pulmonary compartments, highly predictable pharmacokinetics with over 90% of the drug being excreted unchanged in urine, and reliable activity against a broad spectrum of clinically important pathogens, levofloxacin has been used successfully to treat patients with a variety of serious infectious diseases as well as common infections most often treated outside of the hospital setting. Results of clinical trials involving patients with respiratory tract, urinary tract, and skin infections have consistently shown rates of clinical success and bacteriological eradication that were comparable to other widely used broad-spectrum agents. Regimens of levofloxacin, initially involving total daily doses of 250 mg to 500 mg, but more recently regimens involving 750 mg doses, have been shown to be safe and effective. Nearly a decade and a half of clinical experience has defined a safety and tolerability profile that permits data-driven assessment of the risks and benefits of using levofloxacin. As resistance to currently available fluoroquinolones has emerged, the clinical value of levofloxacin deserves continued evaluation. However, consistently high rates of susceptibility of clinically important bacteria, especially among those bacteria that commonly cause respiratory tract infections, such as Streptococcus pneumoniae and Haemophilus influenzae, suggest that this agent will continue to be a widely used well past the 20-year anniversary of its introduction into the antibacterial armamentarium.

Information about ADRs explored by pharmacovigilance approaches: a qualitative review of studies on antibiotics, SSRIs and NSAIDs

Background

Despite surveillance efforts, unexpected and serious adverse drug reactions (ADRs) repeatedly occur after marketing. The aim of this article is to analyse ADRs reported by available ADR signal detection approaches and to explore which information about new and unexpected ADRs these approaches have detected.

Methods

We selected three therapeutic cases for the review: antibiotics for systemic use, non-steroidal anti-inflammatory medicines (NSAID) and selective serotonin re-uptake inhibitors (SSRI). These groups are widely used and represent different therapeutic classes of medicines. The ADR studies were identified through literature search in Medline and Embase. The search was conducted in July 2007. For each therapeutic case, we analysed the time of publication, the strengths of the evidence of safety in the different approaches, reported ADRs and whether the studies have produced new information about ADRs compared to the information available at the time of marketing.

Results

79 studies were eligible for inclusion in the analysis: 23 antibiotics studies, 35 NSAID studies, 20 SSRI studies. Studies were mainly published from the end of the 1990s and onwards. Although the drugs were launched in different decades, both analytical and observational approaches to ADR studies were similar for all three therapeutic cases: antibiotics, NSAIDs and SSRIs. The studies primarily dealt with analyses of ADRs of the type A and B and to a lesser extent C and D, cf. Rawlins' classification system. The therapeutic cases provided similar results with regard to detecting information about new ADRs despite different time periods and organs attacked. Approaches ranging higher in the evidence hierarchy provided information about risks of already known or expected ADRs, while information about new and previously unknown ADRs was only detected by case reports, the lowest ranking approach in the evidence hierarchy.

Conclusion

Although the medicines were launched in different decades, approaches to the ADR studies were similar for all three therapeutic cases: antibiotics, NSAIDs and SSRIs. Both descriptive and analytical designs were applied. Despite the fact that analytical studies rank higher in the evidence hierarchy, only the lower ranking descriptive case reports/spontaneous reports provided information about new and previously undetected ADRs. This review underscores the importance of systems for spontaneous reporting of ADRs. Therefore, spontaneous reporting should be encouraged further and the information in ADR databases should continuously be subjected to systematic analysis.

The risk of coronary heart disease in type 2 diabetic patients exposed to thiazolidinediones compared to metformin and sulfonylurea therapy

PURPOSE

To evaluate whether the risk of coronary heart disease (CHD) differs among adult diabetic patients treated with thiazolidinediones (TZDs) and similar patients treated with combined oral metformin and sulfonylurea (M + S) therapy.

METHODS

We conducted a retrospective cohort study involving 25 140 diabetic patients aged 18 and older who had at least one pharmacy claim for a TZD or combined M + S therapy between 1 January 1999 and 30 June 2002. We used propensity score matching to adjust for observable differences between initiators of combined M + S therapy and TZD initiators. The data were analyzed in two ways: first based on the original matched groups, 'as balanced', without accounting for switching to another medication during follow-up, and second based on actual antidiabetic drug use during follow-up, 'as treated'. Cox proportional hazards regression and multivariable Poisson regression were performed to compare the risk of CHD events.

RESULTS

In the 'as balanced' analysis, the risk for CHD among TZD users relative to combination drug users was close to the null value (adjusted hazard ratio: 1.02, 95% confidence intervals (CI): 0.87-1.20). In the 'as treated' analysis, the risk of CHD was similar for periods of current use of TZDs compared to periods of non-use (incidence rate ratio: 1.10, 95%CI: 0.96-1.25).

CONCLUSIONS

These results do not suggest a cardioprotective or deleterious effects of TZDs compared with combined M + S oral therapy on the short-term CHD event risk in persons with type 2 diabetes after accounting for the greater baseline CHD risk in TZD initiators.

Achilles tendinosis: changes in biochemical composition and collagen turnover rate

BACKGROUND

Understanding biochemical and structural changes of the extracellular matrix in Achilles tendinosis might be important for developing mechanism-based therapies.

HYPOTHESIS

In Achilles tendinosis, changes occur in biochemical composition and collagen turnover rate.

STUDY DESIGN

Descriptive laboratory study.

METHODS

From 10 patients undergoing surgery for Achilles tendinopathy, 1 tendinosis biopsy specimen and 1 biopsy specimen of macroscopically healthy tendon tissue adjacent to the lesion were collected. Furthermore, biopsy samples were collected from 3 donors with asymptomatic Achilles tendons. Water content, collagen content, percentage of denatured collagen, amount of lysine hydroxylation, number of enzymatic and nonenzymatic crosslinks, matrix metalloproteinase activity, and matrix metalloproteinase and collagen gene-expression levels were analyzed.

RESULTS

In tendinotic lesions, the water content was highest, and collagen content was subnormal with higher amounts of denatured/damaged collagen. Low pentosidine levels in tendinotic tissue indicated the presence of relatively young collagenous matrix. More hydroxylated lysine residues were present in tendinotic samples, but enzymatic crosslinks revealed no differences between tendinotic, adjacent, and healthy samples. In tendinotic specimens, matrix metalloproteinase activity was higher, matrix metalloproteinase gene-expression profile was altered, and collagen type I and III gene expression were upregulated.

CONCLUSION

In Achilles tendinosis, the collagen turnover rate is increased, and the natural biochemical composition of the collagenous matrix is compromised.

CLINICAL RELEVANCE

Although tendon tissue directly adjacent to an Achilles tendinosis lesion looks macroscopically healthy, histological and biochemical degenerative changes in adjacent tissue are evident, which may have implications for surgical interventions.

Spontaneous bilateral Achilles tendon rupture in a patient treated with oral levofloxacin

A case of bilateral rupture of the Achilles tendon in a patient treated with levofloxacin for cystitis is reported. A 76-year-old woman suddenly developed painful ankles one day after levofloxacin treatment. Drug therapy was switched to amoxicillin/clavulanate on the fourth day. Sonography revealed a serious condition of tendinosis with complete bilateral full-thickness rupture on day 6. Tendons were both repaired in the same surgical session. Pathological anatomy of the specimens reported fatty tissue lobules with panniculitis and histiocytosis. Ankles were immobilized postoperatively with a plaster cast. Achilles tendon rupture may occur as an adverse side effect of short-term use of levofloxacin, a fluoroquinolone antibiotic. This adverse effect is a rare and poorly understood complication of this antibiotic therapy. A review of the literature is provided.

Gastrointestinal infections in the traveling athlete

Because athletes travel to competitions all over the world, sports medicine providers need to be able to diagnose and treat gastrointestinal infections. Traveler's diarrhea (TD) is by far the most common gastrointestinal illness. TD is a self-limited condition caused by bacteria, viruses, or parasites, and it can easily be treated. Nevertheless, there are preventative measures that should be taken to limit the exposure to TD in the first place.

Evidence of tendinitis provoked by fluoroquinolone treatment: a case-control study

OBJECTIVE

To investigate the association between the use of fluoroquinolone agents and the risk of tendinitis in a large population-based case-control study.

METHODS

The study was performed by linking automated health databases from the Region of Lombardia, Italy. Cases were patients aged > or =18 years who had a hospital discharge diagnosis of non-traumatic tendinitis in 2002-3. For each case, up to five controls were randomly selected among those eligible for inclusion in the study. A conditional logistic regression model was used to estimate the odds ratio of tendinitis associated with the current, recent and past use of fluoroquinolones. Odds ratios were adjusted for exposure to other antibacterials and other drugs.

RESULTS

22,194 cases and 104,906 controls met the inclusion criteria. Current use of fluoroquinolones significantly increased the risk of tendon disorders as a whole (odds ratio [OR] = 1.7; 95% CI 1.4, 2.0), tendon rupture (OR = 1.3; 95% CI 1.0, 1.8) and rupture of the Achilles' tendon (OR = 4.1; 95% CI 1.8, 9.6). Concomitant use of corticosteroids and fluoroquinolones increased the risk of both tendon rupture (OR = 3.1; 95% CI 1.5, 6.3) and rupture of the Achilles' tendon (OR = 43.2; 95% CI 5.5, 341.1).

DISCUSSION

Evidence that exposure to fluoroquinolones is associated with the sudden occurrence of tendinitis is supported by this large population-based study. We can estimate that a single case of rupture of the Achilles' tendon would occur for every 5958 persons treated with fluoroquinolones (95% CI 2148, 23,085). The corresponding number needed to harm is 979 (95% CI 122, 9172) for patients who concomitantly use corticosteroids and 1638 (95% CI 351, 8843) for those aged >60 years.

CONCLUSION

Clinicians should be aware of this adverse effect, and the increased risk for fluoroquinolone-associated tendinitis in elderly patients with corticosteroid use must be considered when these agents are prescribed.