Transforaminal lumbar interbody fusion vs. posterolateral instrumented fusion: cost-utility evaluation along side an RCT with a 2-year follow-up.

PURPOSE: Long-lasting low back pain is an increasing problem, and for some patients surgery is the final option for improvement. Several techniques for spinal fusion are available and the optimal technique remains uncertain. The objective of this study was to assess the cost-effectiveness and cost-utility of transforaminal lumbar interbody fusion (TLIF) compared to posterolateral instrumented fusion (PLF) from the societal perspective. METHODS: 100 Patients were randomized to TLIF or PLF (51/49) and followed for 2 years. Cost data were acquired from national registers, and outcomes were measured using the Oswestry Disability Index and SF-6D questionnaires. Conventional cost-effectiveness methodology was employed to estimate net benefit and to illustrate cost-effectiveness acceptability curves. The statistical analysis was based on means and bootstrapped confidence intervals. RESULTS: Results showed no statistically significant difference in either cost or effects although a tendency for the TLIF regimen being more costly on bed days (2,554) and production loss (1,915) was observed. The probability that TLIF would be cost-effective did not exceed 30 % for any threshold of willingness to pay per quality-adjusted life year. Sensitivity analysis was conducted and supported the statistical model for handling of missing data. CONCLUSION: TLIF does not seem to be a relevant alternative to PLF from a socioeconomic, societal point of view.

Metabolic studies in total parenteral nutrition with lipid in man. Comparison with glucose.

A study was undertaken of patients on a regimen of total parenteral nutrition comparing the nitrogen balance, energy substrates, blood amino acids, immunoreactive insulin, and immunoreactive glucagon levels during the sequential infusion of nonprotein calories as either glucose alone (glucose system) or 83% as Intralipid (Pharmacia Fine Chemicals, Montreal, Canada) and 17% glucose (lipid system). These nonprotein calories were administered with a constant background of amino acids (1 g/kg per day), vitamins, and minerals. Each system was infused for a week at a time and the order of infusion randomized. In some patients whole blood arteriovenous (A-V) levels of amino acids were measured across forearm muscle. During the glucose system there was a significantly higher level of pyruvate, lactate, alanine, and immunoreactive insulin, consistent with glucose being the principal source of energy. In contrast, during the lipid system there was a rise in free fatty acids and ketone bodies with a fall in insulin, suggesting that lipid was now the principal source of energy. Despite these two very diverse metabolic situations the nitrogen balance with both systems was positive to a comparable degree after the establishment of equilibrium. Correspondingly, A-V differences of whole blood amino acid nitrogen showed uptake by muscle to an equivalent degree with both systems. Clinical studies indicated that the lipid system as defined herein could be infused by peripheral vein for up to 43 days with resultant weight gain, elevation of serum proteins, and healing of fistulae. Our studies suggest that for both metabolic and clinical reasons exogenously infused lipid is a suitable source of nonprotein calories.