5.6. Cost-effectiveness of the treatments in subgroups (V)
After adjustment for baseline differences and duration of symptoms, the total costs during the 1 year follow-up period did not differ between the two treatment groups. At the 4-week follow-up assessment, therapy visits (physiotherapists and osteopaths; P<0.05) and drug cost (P = 0.005) were significantly less in the methylprednisolone group. From the 4-week follow-up onward, no significant cost differences between the treatments emerged at any time point. At 1 year, the mean cumulative cost per patient was $2195 (95% CI 1729–2661) in the steroid group and $2180 (95% CI 1694–2666) in the saline group. No differences in cost-effectiveness between the treatments were observed. After 1 month only, one patient in the saline group underwent surgery, and by 1 year 18 patients in the methylprednisolone group and 15 in the saline group received surgical treatment.
For bulges, no differences between the treatments in the medical costs or sick leaves were observed. Cost-effectiveness of the treatments was likewise similar: to obtain one painless patient at 1 year cost with steroid $3740 vs. $3629 with saline (Table 5).
5.6.1. Contained herniations
For contained herniations, the steroid intervention produced savings in the need for homecare ($200 per patient; 95% CI, $46 to $355, P = 0.013) at 4 weeks and for total costs at 6 months ($1795; 95% CI, $1069 to $2521, P < 0.001). Medical costs at each follow-up are presented in Figure 7A. By 1 year, 42 % of patients were operated in the saline group vs. 20 % in the steroid group (p = 0.1). When the rate of operations was evaluated by Kaplan-Meier curves and log-rank tests, p-value of 0.1 was obtained (Figure 8). Because of the different operation rate, days on sick leave by 6 months (7.4 days per month per patient; 95% CI, 2.3–12.5 days, p = 0.006) and cumulative costs at 12 months ($1969 per patient; 95% CI, $590 to $2914, P = 0.007) were in favor of steroid. The AUC-scores of medical costs from 3 to 12 months were also in favor of the steroid treatment (p < 0.001) in accordance with the other data.
No significant short-term differences were observed in cost-effectiveness, but by 12 months to obtain one painless patient cost $12666 less per patient in the steroid group (p < 0.01; Table 5).
Table 5. Mean cumulative costs ($) of periradicular infiltration per one responder (≥ 75% decrease of leg pain) according to MRI-classification*.
| Timepoint | Bulges | Contained herniations | Extrusions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Steroid | Saline | p | Steroid | Saline | p | Steroid | Saline | p | |||
| Three months | 2640 | 2116 | NS | 5850 | 6360 | NS | 4081 | 2230 | NS | ||
| Twelve months | 3740 | 3629 | NS | 4432 | 17098 | 0.0073 | 7165 | 2484 | 0.0058 | ||
| * Operated patients were always regarded as non-responders. Statistical significance evaluated by Student’s t-test. MRI = magnetic resonance imaging, NS = not significant. | |||||||||||
5.6.2. Extrusions
For extrusions, cost of therapy visits at 4 weeks was significantly less with the steroid injection ($182; 95% CI, $79 to $285, P = 0.001). Medical costs at each follow-up assessment are presented in Figure 7B. By 1 year, 13 % underwent surgery in the saline group vs. 32 % in the steroid group (chi-square value 3.9, df 1, p = 0.05). By Kaplan-Meier analysis, p-value was 0.1 (Figure 8). Because of the higher operation rate in the steroid group, the area-under-the-curve scores of medical costs from 3 to 12 months were significantly (P = 0.004) in favor of saline, whereas for cumulative costs at 12 monts only a trend (P = 0.08) in favor of saline existed. No significant differences in sick leaves were observed.
No significant short-term differences were observed in cost-effectiveness, but by 12 months the steroid treatment was more expensive: $4445 more per one painless patient (P<0.01; Table 5).
Figure 7. Medical costs ($, standard deviations indicated with vertical bars) at each follow-up assessment after the periradicular infiltration with either methylprednisolone–bupivacaine ( • ) or saline (— • —). The upper box presents the number of patients at each follow-up assessment. A) Subgroups of contained herniations, B) extrusions. * P-value of the between-group treatment difference at the respective follow-up <0.05, **p<0.01.
5.6.3. Disc level
Steroid treatment was superior to the saline at the 4-week follow-up assessment with respect to need for homecare at the L3–4–5 level ($120; 95% CI, $31 to $209, P = 0.01). No significant differences with respect to cumulative medical costs, rate of operations or work absenteism or cost-effectiveness were observed between the treatments.