The economic impact of blue-light filtering intraocular lenses on age-related macular degeneration associated with cataract surgery: a third-party payer's perspective

OBJECTIVES: Epidemiological data support an association between age-related macular degeneration (AMD) and cataract surgery that may be attributed to post-operative blue light exposure. By limiting the retina's blue light exposure, new blue-light filtering intraocular lenses (BLF IOLs) have the potential to reduce the development of AMD following cataract surgery. In the current economic healthcare environment, there is increased interest in the cost impact of new medical technologies. The objective of this analysis was to evaluate the cost impact of a BLF IOL versus a non-BLF IOL in cataract surgery. METHODS: An economic model was developed to emulate three age-specific cohorts and to assess the clinical and economic outcomes over 5 years. Data from the published literature was supplemented with clinical expert opinion. Key literature inputs involved the risk of AMD after cataract surgery as well as laboratory and animal data on the effectiveness of the BLF IOL in reducing the risk of AMD. Clinical experts provided information on the management of AMD. Direct medical costs including the cost of the IOL, monitoring, and AMD prophylaxis and treatment were incorporated into the model. All costs were standardized to 2004 US dollars. Age-stratified sensitivity analyses were conducted. RESULTS: In the BLF IOL group, the 5-year age-stratified incidence of AMD ranged from 0.58 to 9.23 per 100 eyes, compared with 1.69 to 24.55 per 100 eyes in the non-BLF IOL group. The incremental cost of the BLF was offset by reduced costs associated with averted AMD treatment. Estimated savings with BLF IOLs per 100 eyes were $4275, $29 997, and $111 734 in the 55 to 64 year-old, 65 to 74 year-old, and >or= 75-year-old cohorts, respectively; these findings remained robust throughout the sensitivity analyses. CONCLUSION: Limitations of this analysis include the lack of prospective clinical trial data that definitively demonstrate the efficacy of a BLF IOL in preventing AMD. Moreover, the efficacy data used to populate the model were derived from laboratory and animal studies. Thus, based on preliminary data, this study suggests that the economic benefits of implanting BLF IOLs during cataract surgery are observed in all patients over a 5-year timeframe although cost savings are greatest in patients >or= 75 years.     

Paradoxical facilitation of acetylcholine release from parasympathetic nerves innervating guinea-pig trachea by isoprenaline.

1. Previous studies have provided evidence that activation of beta-adrenoceptors on cholinergic nerve terminals can inhibit neurotransmission in the airways. However, in most cases, this conclusion has been based on indirect evidence obtained from mechanical experiments where changes in airways smooth muscle tone were measured. 2. We have assessed whether modulation of cholinergic neurotransmission by beta-adrenoceptor agonists is due to a pre- or post-junctional action by investigating the effect of isoprenaline on contractile responses evoked by exogenous acetylcholine (ACh) and electrical field stimulation (EFS; 4 Hz, 40 V, 0.5 ms pulse width every 15 s), and on EFS-induced ACh release from cholinergic nerves innervating guinea-pig and human trachea. Furthermore, the subtype of beta-adrenoceptor which modulates neurotransmission and the potential role of cyclic AMP in this response were evaluated. 3. In guinea-pig trachea, isoprenaline (1 nM-1 microM) inhibited the contractile response evoked by exogenous ACh (1 microM) to a similar extent to that evoked by EFS (EC50 = 19.9 and 23 nM, respectively). 4. In epithelium-denuded guinea-pig strips treated with indomethacin (10 microM), isoprenaline significantly enhanced EFS-induced ACh release from cholinergic nerve terminals (by 36% at 0.3 microM). This effect was blocked by propranolol and ICI 118, 551 (each 0.1 microM). In contrast, isoprenaline failed to affect EFS-induced ACh release from parasympathetic nerves innervating human trachea. 5. To evaluate the role of cyclic AMP in the beta-adrenoceptor-induced facilitation of cholinergic neurotransmission, the effects of various cyclic AMP elevating drugs on ACh release were studied. Forskolin (10 microM) significantly augmented (by 17%) EFS-induced ACh release, an effect which was not reproduced by 1,9-dideoxyforskolin (10 microM) which does not activate adenylyl cyclase. Similarly, the cyclic AMP analogue, 8-bromo-cyclic AMP (1 mM) and cholera toxin (1 microgram ml-1) facilitated ACh output by 22 and 47% respectively, whereas prostaglandin E2 (PGE2, 0.1 nM-1 microM) inhibited this response (by 67% at 1 microM). 6. Zardaverine (10 microM), a dual inhibitor of the phosphodiesterase (PDE)3 and PDE4 isoenzyme families, did not affect EFS-induced ACh release and failed to facilitate the actions of either isoprenaline or PGE2. Similarly, neither SK&F 94120 (10 microM) nor rolipram (10 microM), selective inhibitors of PDE3 and PDE4 respectively, significantly affected the release of ACh in response to EFS. 7. The result of this study suggests that isoprenaline facilitates cholinergic neurotransmission in guinea-pig, but not human, trachea by activation of pre-junctional beta 2-adrenoceptors, an effect that may be mediated via activation of the cyclic AMP/cyclic AMP-dependent protein kinase cascade. Furthermore, the data presented herein illustrate the need to undertake direct measurements of neurotransmitter release when examining the effect of agents purported to act pre-junctionally.     

Epidemiologie von Schilddrüsenerkrankungen in Deutschland

Background

Germany is an iodine-deficient region. Iodine deficiency was classified as moderate in the North and as severe in mountain regions in Southern Germany. Improved legislation involving the iodization of table salt became effective during the 1990s. This legislation has contributed considerably to an increase in the use of iodized salt for food production.

Current results

The population is currently supplied with iodine at a lower recommended level. From an epidemiological point of view, Germany is a region characterized by the change from iodine deficiency to iodine sufficiency. Typical for this transformation, one might expect a low prevalence of goitre among children and adolescents, while there would still be a high prevalence of goitre, thyroid nodules, and subclinical hyperthyroidism among the elderly. In a representative German sample of children and adolescents, however, relatively large thyroid volumes have been found.

Conclusion

Systematic monitoring programs for thyroid disorders, including measurements of urinary iodine excretion in population samples, allow the detection of deviations in the iodine supply and are thus an obligatory precondition for the effective prevention of iodine deficiency.     

Impact of stress reduction on negative school behavior in adolescents

Background  

The purpose of this study was to determine the effect of stress reduction via the Transcendental Meditation program on school rule infractions in adolescents.     

Infectivity of Plasmodium falciparum gametocytes to Anopheles arabiensis after treatment with sulfadoxine-pyrimethamine

Sulfadoxine-pyrimethamine induces increased gametocytaemia when used for treating Plasmodium falciparum malaria. Laboratory-reared Anopheles arabiensis mosquitoes were fed with blood from patients with post-therapeutic gametocytaemia using a membrane feeder. Fourteen days later the heads and thoraxes of 613 mosquitoes were negative for P. falciparum sporozoites by enzyme-linked immunosorbent assay.     

Mutated alleles of the rod and cone Na-Ca+K-exchanger genes in patients with retinal diseases

PURPOSE: To study the possible involvement of the rod (SLC24A1) and cone (SLC24A2) Na-Ca+K exchanger (NCKX) genes in retinal diseases. METHODS: DNA was collected from unrelated patients with retinal disease, mainly from North America. A human genomic library was screened with the cone NCKX cDNA, and hybridizing clones were sequenced to determine the genomic organization of the SLC24A2 gene. The single-strand conformation polymorphism (SSCP) technique and direct sequencing were used to screen the patients' DNA for mutations in SLC24A1 and SLC24A2. The effect of selected missense changes on protein function was tested by measuring potassium-dependent Na-Ca exchange of the mutant proteins expressed in insect cells. RESULTS: Twenty-seven novel sequence changes were found in the rod NCKX gene, 21 of which are unlikely to be pathogenic, because they did not cosegregate with the disease or did not affect conserved regions of the protein. Of the remaining six, two were frameshift mutations found in one patient each. If translated, these alleles would encode nonfunctional proteins. Three of the six possibly pathogenic mutations were missense changes located in conserved regions, and their protein functions were assayed. Only one (Ile992Thr) had a significantly low level of exchanger function, but it was found in two unrelated patients who were heterozygotes with different retinal diseases, and this mutation could not be unequivocally associated with either disease. The last of the six changes is likely to create a new splice acceptor site. The genomic organization of the cone NCKX gene was determined, and it contained 11 exons with a few splice variants. Fifteen novel sequence changes were identified in the cone exchanger gene in patients with a cone dysfunction or degeneration. Only three of these sequence changes, all missense changes found in heterozygous patients, were considered possibly pathogenic. Functional analysis showed only a slight reduction in the activity of the corresponding mutant proteins. CONCLUSIONS: Although variant alleles of the rod and cone NCKX genes were found, none could be definitively associated with a specific retinal disease. The human phenotype associated with mutant exchanger alleles remains unknown.     

A new method and device to induce transient retinal ischemia in the rat

PURPOSE: To describe and characterize a novel, non-invasive method to induce retinal ischemia in the rat. METHODS: Retinal ischemia was produced by applying a compression force with a suture thread anchored about 2mm behind the limbus of the eye in order to increase intraocular pressure and reduce ocular blood flow. Both ends of the suture thread were connected to weights via a pulley system. The effect of various weights (20, 25, or 35 g) on retinal damage was tested in animals of different body weights (350 and 574 g). Scotopic ERG measurements and histological sections of retinal tissue were used to evaluate possible functional and morphological changes to the retina as a consequence of ischemia followed by reperfusion. RESULTS: Retinal ischemia was achieved by this method with good reproducibility. The degree of retinal damage, as quantified by ERG measurement, correlated with the amount of weight connected to the suture thread. Seven days after 60 minutes of retinal ischemia, the amplitudes of A- and B-waves of eyes compressed with a 20 g weight were 84 +/- 11% and 86 +/- 16% (mean +/- SEM, n = 4, amplitudes before ischemia defined 100%), respectively. The A- and B-wave amplitudes of eyes compressed with 25 g were 69 +/- 7% and 76 +/- 6% (n = 11), respectively. A 35 g treatment produced A- and B-wave amplitudes of 55 +/- 3.9% and 52 +/- 4% (n = 35), respectively. There was no significant difference in the level of ischemic damage in the two groups of animals with different body weights evaluated in this study. At two weeks after 60-minute retinal ischemia, there was a significant decrease (by 31.1%) in the cell density in the retinal ganglion cell layer. CONCLUSIONS: The pulley method is an easy, non-invasive, and highly reproducible technique for inducing retinal ischemia in rats. This procedure may provide a useful animal model of ischemic retinopathy.