Estimating incidence and prevalence rates of chronic diseases using disease modeling

The transmission mechanism theory of disease dynamics: Its aims, assumptions and limitations

Most of the progress in the development of single scale mathematical and computational models for the study of infectious disease dynamics which now span over a century is build on a body of knowledge that has been developed to address particular single scale descriptions of infectious disease dynamics based on understanding disease transmission process. Although this single scale understanding of infectious disease dynamics is now founded on a body of knowledge with a long history, dating back to over a century now, that knowledge has not yet been formalized into a scientific theory. In this article, we formalize this accumulated body of knowledge into a scientific theory called the transmission mechanism theory of disease dynamics which states that at every scale of organization of an infectious disease system, disease dynamics is determined by transmission as the main dynamic disease process. Therefore, the transmission mechanism theory of disease dynamics can be seen as formalizing knowledge that has been inherent in the study of infectious disease dynamics using single scale mathematical and computational models for over a century now. The objective of this article is to summarize this existing knowledge about single scale modelling of infectious dynamics by means of a scientific theory called the transmission mechanism theory of disease dynamics and highlight its aims, assumptions and limitations.

Intra-articular platelet-rich plasma injections versus intra-articular corticosteroid injections for symptomatic management of knee osteoarthritis: systematic review and meta-analysis

Background

Intra-articular (IA) corticosteroid (CS) injections are the mainstay of treatment for symptomatic management in knee osteoarthritis (OA), particularly in the UK. IA platelet-rich plasma (PRP) injections are a promising alternative, but no systematic reviews to date have compared them to the current standard of care, IA CS injections. We aim to investigate the effect of IA PRP injections versus IA corticosteroid injections for the symptomatic management of knee OA.

Methods

All published trials comparing IA PRP and CS injections for knee OA were included. MEDLINE, EMBASE, Scopus and Web of Science were searched through June 2020. Risk of bias was assessed using the Cochrane Risk of Bias tool. A random effects model was used to calculate standardized mean difference with 95% confidence interval in WOMAC/VAS score (or subscores), comparing IA PRP to CS injections across studies.

Results

Included were eight studies and 648 patients, 443 (68%) were female, mean age 59 years, with a mean BMI of 28.4. Overall, the studies were considered at low risk of bias. Compared with CS injections, PRP was significantly better in reducing OA symptoms (pain, stiffness, functionality) at 3, 6 and 9 months post-intervention (P < 0.01). The greatest effect was observed at 6 and 9 months (− 0.78 (− 1.34 to − 0.23) standard mean deviations (SMD) and − 1.63 (− 2.14 to − 1.12) SMD respectively). At 6 months, this equates to an additional reduction of 9.51 in WOMAC or 0.97 on the VAS pain scales. At 6 months PRP allowed greater return to sporting activities than CS, measured by the KOOS subscale for sporting activity, of magnitude 9.7 (− 0.45 to 19.85) (P = 0.06). Triple injections of PRP, generally separated by a week, were superior to single injections over 12 months follow-up (P < 0.01).

Conclusions

IA-PRP injections produce superior outcomes when compared with CS injections for symptomatic management of knee OA, including improved pain management, less joint stiffness and better participation in exercise/sporting activity at 12 months follow-up. Giving three IA-PRP, with injections separated by a week, appears more effective than 1 IA-PRP injection.

Prospero trial registration number

CRD42020181928.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04308-3.

Disease modeling for public health: added value, challenges, and institutional constraints

Public health policymakers face increasingly complex questions and decisions and need to deal with an increasing quantity of data and information. For policy advisors to make use of scientific evidence and to assess available intervention options effectively and therefore indirectly for those deciding on and implementing public health policies, mathematical modeling has proven to be a useful tool. In some areas, the use of mathematical modeling for public health policy support has become standard practice at various levels of decision-making. To make use of this tool effectively within public health organizations, it is necessary to provide good infrastructure and ensure close collaboration between modelers and policymakers. Based on experience from a national public health institute, we discuss the strategic requirements for good modeling practice for public health. For modeling to be of maximal value for a public health institute, the organization and budgeting of mathematical modeling should be transparent, and a long-term strategy for how to position and develop mathematical modeling should be in place.

Immunophenotyping of a Stromal Vascular Fraction from Microfragmented Lipoaspirate Used in Osteoarthritis Cartilage Treatment and Its Lipoaspirate Counterpart

Osteoarthritis (OA) is a degenerative joint disease accompanied by pain and loss of function. Adipose tissue harbors mesenchymal stem/stromal cells (MSC), or medicinal signaling cells as suggested by Caplan (Caplan, 2017), used in autologous transplantation in many clinical settings. The aim of the study was to characterize a stromal vascular fraction from microfragmented lipoaspirate (SVF-MLA) applied for cartilage treatment in OA and compare it to that of autologous lipoaspirate (SVF-LA). Samples were first stained using a DuraClone SC prototype tube for the surface detection of CD31, CD34, CD45, CD73, CD90, CD105, CD146 and LIVE/DEAD Yellow Fixable Stain for dead cell detection, followed by DRAQ7 cell nuclear dye staining, and analyzed by flow cytometry. In SVF-LA and SVF-MLA samples, the following population phenotypes were identified within the CD45⁻ fraction: CD31⁺CD34⁺CD73^±CD90^±CD105^±CD146^± endothelial progenitors (EP), CD31⁺CD34⁻CD73^±CD90^±CD105⁻CD146^± mature endothelial cells, CD31⁻CD34⁻CD73^±CD90⁺CD105⁻CD146⁺ pericytes, CD31⁻CD34⁺CD73^±CD90⁺CD105⁻CD146⁺ transitional pericytes, and CD31⁻CD34⁺CD73^highCD90⁺CD105⁻CD146⁻ supra-adventitial-adipose stromal cells (SA-ASC). The immunophenotyping profile of SVF-MLA was dominated by a reduction of leukocytes and SA-ASC, and an increase in EP, evidencing a marked enrichment of this cell population in the course of adipose tissue microfragmentation. The role of EP in pericyte-primed MSC-mediated tissue healing, as well as the observed hormonal implication, is yet to be investigated.

The Effect of Intra-articular Injection of Autologous Microfragmented Fat Tissue on Proteoglycan Synthesis in Patients with Knee Osteoarthritis

Osteoarthritis (OA) is one of the leading musculoskeletal disorders in the adult population. It is associated with cartilage damage triggered by the deterioration of the extracellular matrix tissue. The present study explores the effect of intra-articular injection of autologous microfragmented adipose tissue to host chondrocytes and cartilage proteoglycans in patients with knee OA. A prospective, non-randomized, interventional, single-center, open-label clinical trial was conducted from January 2016 to April 2017. A total of 17 patients were enrolled in the study, and 32 knees with osteoarthritis were assessed. Surgical intervention (lipoaspiration) followed by tissue processing and intra-articular injection of the final microfragmented adipose tissue product into the affected knee(s) was performed in all patients. Patients were assessed for visual analogue scale (VAS), delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and immunoglobulin G (IgG) glycans at the baseline, three, six and 12 months after the treatment. Magnetic resonance sequence in dGEMRIC due to infiltration of the anionic, negatively charged contrast gadopentetate dimeglumine (Gd-DTPA²⁻) into the cartilage indicated that the contents of cartilage glycosaminoglycans significantly increased in specific areas of the treated knee joint. In addition, dGEMRIC consequently reflected subsequent changes in the mechanical axis of the lower extremities. The results of our study indicate that the use of autologous and microfragmented adipose tissue in patients with knee OA (measured by dGEMRIC MRI) increased glycosaminoglycan (GAG) content in hyaline cartilage, which is in line with observed VAS and clinical results.