Purchasing a new instrument in a clinical laboratory is an expensive proposition. Consideration must be given not only to the cost to purchase the instrument, but also to the cost to maintain (service contracts), the cost of ancillary supportive processes (information technology and interfaces), and the cost of environmental issues (chemical hazard preparation and disposal). In addition, consideration of the impact it will have on current workflow, including “hands-on” time and impact on replacing older technology is key. Where possible, determining the overall outcome to patient care should be a priority in selecting newer methodology in the laboratory.
The most common and easiest way to cost justify the MALDI-TOF MS is to evaluate current practices:
1. Direct comparison to costs associated with biochemical tests and methods currently used to identify microorganisms
A great example of this is found in publications by Gaillot et al. (2011) and Tan and colleagues (2012):
Gaillot and team assessed the cost of performing their routine VITEK® 2/API® identification (ID) systems to MALDI-TOF MS. Comparing costs for one year pre-MALDI-TOF MS to one year post-MALDI-TOF MS, the total for ID pre-MALDI-TOF MS was $193,000, compared to $21,000 in the post-MALDI-TOF MS period. An additional $5,000 was also incurred in the post-MALDI period for supplemental ID assays. For over 33,000 isolates in the pre-MALDI era versus over 38,000 isolates in the post-MALDI era, the average costs were $5.81 for conventional ID versus $0.41 for MALDI-TOF MS ID. At 38,000 isolates with an annual savings of $205,000, it was easy to cost-justify the instrument.2
The scientists from Johns Hopkins evaluated a total of 952 isolates (824 bacterial isolates and 128 yeast isolates) recovered from 2,214 specimens using a MALDI-TOF MS. When compared to standard phenotypic identifications, MALDI-TOF MS provided IDs 1.45 days earlier on average (P <0.001) as seen in the graph on the top right. They projected that the incorporation of the MALDI protocol would reduce reagent and labor costs of ID by $102,424 (56.9%) within 12 months. They provide a comprehensive cost analysis model that can be generalized to other moderate- to high-volume laboratories.3
Another excellent example is cost savings in laboratory professionals' time, better turnaround time, and overall cost savings to the laboratory with a defined patient population, such as cystic fibrosis. Time to ID with 47 bacterial isolates from 24 cystic fibrosis patients showed ID of 85% of isolates by MALDI-TOF MS at 48 hours of incubation, compared to only 34% with conventional methods. In addition, the ability to definitively identify the Burkholderia species and non-fermenting Gram-negative rods was a distinct advantage over phenotypic methods.4
2. Cost avoidance: Assessing outcomes
Using MALDI-TOF MS ID for early diagnosis of gram-negative bacteremia, Perez and coworkers compared over 100 patients in their pre- and post-MALDI-TOF MS era. They showed improved time for ID (22.7 hours earlier), better utilization of antibiotic therapy (time to optimal therapy from 75 to 29 hours), decreased length of stay for the patient (over two days), and decreased total hospital costs of over $19,000 per patient.5
2. Gaillot O, Blondiaux N, Loïez C, Wallet F, Lemaître N, Herwegh S, Courcol RJ. "Cost-effectiveness of switch to matrix-assisted laser desorption ionization-time of flight mass spectrometry for routine bacterial identification." J Clin Microbiol. 2011;49(12):4412. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3232935/.3. Tan K E, Ellis BC, Lee R, Stamper PD, Zhang SX, Carroll KC. "Prospective evaluation of a matrix-assisted laser desorption ionization-time of flight mass spectrometry system in a hospital clinical microbiology laboratory for identification of bacteria and yeasts: a bench-by-bench study for assessing the impact on time to identification and cost-effectiveness." J Clin Microbiol. 2012;50(10):3301–3308. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3457442/.4. Desai AP, Stanley T, Atuan M, McKey J, Lipuma JJ, Rogers BE, Jerris, R. "Use of matrix assisted laser desorption ionisation-time of flight mass spectrometry in a paediatric clinical laboratory for identification of bacteria commonly isolated from cystic fibrosis patients." J Clin Pathol. 2012;65(9):835-838. Available at: http://jcp.bmj.com/content/65/9/835.long.5. Perez KK, Olsen RJ, Musick WL, Cernoch PL, Davis JR, Peterson LE, Musser J M. "Integrating rapid diagnostics and antimicrobial stewardship improves outcomes in patients with antibiotic-resistant Gram-negative bacteremia." J Infect. 2014;69(3):216-225. Available at: http://www.journalofinfection.com/article/S0163-4453(14)00134-0/fulltext.
