This study was a retrospective longitudinal study aiming at measuring the burden of PVP/PKP due to OVCF in China from the payer perspective. To our knowledge, our study was the first to estimate the utilisation of PVP/PKP procedures and their costs for OVCF treatment in China by analysing real-world city-wide claims data. We noted the utilisation of PVP/PKP was high for OVCF patients with 28.66% PVP/PKP surgery rate and 7.95% 2-year cumulative re-surgery rate. Median LOS in hospitals was 9 days, and median time interval to re-surgery was 139 days. Hospitalisation costs due to PVP/PKP were high: per hospitalisation cost averaged 35,906 CNY (5,122 USD), and annual hospitalisation costs in the metropolitan city totalled 187 million CNY (27 million USD). It brought a significant burden to both medical insurance institution and patients.
Subgroup analyses and sensitivity analysis indicated that men had shorter hospital stays but higher hospital costs than women. In addition, there was no difference in reoperation rates between men and women. With the increase of age, both LOS and the re-surgery rates increased (the sudden drop in the re-surgery rate in 90+ age group might be due to the impact of sample size, mortality, etc.). However, the costs of hospitalisation for the 50-59 age group were the highest, which emphasized the value of early intervention for osteoporosis.
Overall, the results of this study were comparable with those of previous studies. In this study, the number of female OVCF patients was about 2.3 times that of male patients, which is consistent with the higher risk of OVCF in females in other studies (1,4,8,22). The surgery rate of PVP/PKP in OVCF patients in our study was also similar to the finding of another study at 23.1% (23). A comparison of re-surgery rate among studies was not conducted due to the lack of studies on PVP/PKP re-surgery rates.
Whether it is PVP or PKP, surgery-related inpatient costs are high. In contrast, taking a short-term view, PVP seems to be better than PKP because there was no significant difference in the re-surgery rate between PVP and PKP, but the costs of PVP were nearly 30% lower than that of PKP. Another clinical study in China also recommended PVP because the clinical result (pain relief) differed little but the costs of PKP were higher (24). However, due to the lack of confounder control in this study, we should be more cautious about asserting a causal relationship between surgery types and the outcomes. The costs associated with vertebral fractures in many countries are well documented: in America, the costs per surgery-related hospitalisation were 7,805 USD (54,713 CNY) for PVP and 12,032 USD (84,344 CNY) for PKP in 2006, 9,837 USD (68,957 CNY) for PVP and 13,187 USD (92,441 CNY) for PKP in 2007 and 2008 (25,26). The results of US studies are similar to our study, where the costs of PKP hospitalisation were higher than PVP. However, it is worth noting that in terms of long-term costs, the results are reversed. In America, the two-year cumulative costs were 44,496 USD (311,917 CNY) for PVP and 41,339 USD (289,786 CNY) for PKP between 2006 and 2010 (27). In Germany, patients’ four-year cumulative costs were 42,510 EUR (330,775 CNY/47,186USD) for PVP and 39,014 EUR (303,529 CNY/43,306USD) for PKP between 2006 and 2010 (28). One reason is that patients with PKP surgery use fewer drugs and pay lower maintenance costs after surgery. PKP significantly reduced 6.8%-7.9% treatment costs during the 2-year post-surgery periods in America and reduced 33% painkiller costs during the 4-year post-surgery periods in German (27,28). The surgical sequelae and its burden would be an interesting point for future research.
Aside from surgery intervention, conservative treatment for OVCF is widely employed in China. Conservative treatment is recommended for mild/chronic OVCF, while severe/acute OVCF is treated by surgery (29). Anticoagulant therapy of low molecular weight heparin calcium injection can be given during bed rest; non-steroidal anti-inflammatory analgesics are mainly used to relieve acute pain; anti-osteoporosis medication, such as alendronate sodium, and complex calcium carbonate vitamin D tablets can also be employed (29,30). In terms of treatment effect, for pain relief, the short-term effect of surgery is better than that of conservative treatment, but no difference was observed in terms of long-term effect (31-35). Recently, a study indicated that conservative treatment with anabolic drug could achieve comparative outcomes than PVP/PKP in treating acute OVCF (36). However, from the perspective of recovery of vertebral stability and vertebral height, surgery is superior to conservative treatment (34).
Although successful PVP/PKP treatment for OVCF can effectively alleviate pains and other symptoms, the procedures are not free of untoward effects. Studies have explored that the PVP/PKP may accelerate local bone absorption due to bone cement, thereby increasing the risk of recurrent fracture of the surgical vertebra (37–40). In addition, studies also reported that additional stress of adjacent vertebrae caused by the cement augmentation and cement leakage are important factors in causing new adjacent vertebral fractures after PVP/PKP (41–44).
To avoid OVCF, anti-osteoporosis therapy should be considered as primary prevention. Osteoporosis and resulting osteoporotic vertebral fractures typically develop silently with a long-time window from the initial decrease in bone density to the occurrence of OVCF. Use of anti-osteoporosis drugs can reduce the risk of fractures. For women with osteoporosis but without vertebral fractures, alendronate significantly reduced the first vertebral fracture by 44% (45). Studies have shown that anti-osteoporosis treatment after fracture can reduce the risk of re-fracture by 40% within three years (46). In this regard, anti-osteoporosis treatment should be considered as part of long-term treatment strategies to reduce the risk of fracture (47-50). Although anti-osteoporosis therapy plays a significant role in OVCF prevention, the current situation of drug use is not optimistic. This might be due to the low diagnosis rate of osteoporosis and vertebral fractures. What’s more, there is a large gap in the diagnosis and prevention of osteoporosis and vertebral fractures among different level hospitals, especially in community hospitals where the diagnosis ability is poor. Although inadequate diagnosis and prevention of osteoporosis is consensus, related real-world studies are lacking. The insufficiency of osteoporosis diagnosis and prevention can only be indirectly understood from the situation of fracture patients. A study in mainland China showed only 13.9% of patients used anti-osteoporosis drugs before fractures (23). Moreover, a retrospective study showed that in China, the rate of misdiagnosis of vertebral fractures was 54.27%; while in the patients with vertebral fractures diagnosis, 61.33% were definitely diagnosed as osteoporosis or OVCF, and only 28% were given anti-osteoporosis therapy (51). Compounding the problem is poor compliance with the medications as short-term medication intake has no evidentiary clinical benefits for fracture prevention (52-54). In China, an analysis of medical insurance claims database from 2009 to 2010 showed that the adherence to bisphosphonate treatment was even worse with the mean Medication Possession Ratio (MPR) being 0.34, 0.22, and 0.15 at the 3rd, 6th, and 12th month over the follow-up period, respectively; moreover, only 2.1% patients were observed with high adherence (MPR>0.8) during the 12-month follow-up (55).
The strength of our study stems from a well-defined study population which was population-based, i.e. residents of the metropolitan city covered by government health insurance were all included. The findings are likely to be more robust than those derived from a single hospital or hospitals from convenient sampling. Nevertheless, our study also has a number of limitations. On the one hand, some of the shortcomings of this study are due to the limitations of the database. Mortality and comorbidity are important in health research. However, our study was based on administrative claim database which was unable to support research about survival of patients in real world. Besides, claim database lacks detailed medical information in terms of comorbidity. In addition, researchers should be cautious about extrapolating findings to other regions or cities in China or to patients without health insurance because of variation in adopting surgical intervention for OVCF, health insurance coverage schemes and steep costs for self-paying patients. On the other hand, study design can lead to some estimation bias. First, we assumed all vertebral fracture cases meeting eligibility criteria were osteoporotic. This may include a few patients with non-osteoporotic vertebral fractures. In order to justify the assumption, we ran the sensitivity analysis among patients who had established OVCF diagnosis. The results were in line with those in the main analysis, which proves that our assumption is reliable. Second, there may be omissions in selecting PVP/PKP patients due to the lack of standardized procedure name, which would lead to the under-estimation of the surgery rate. Third, re-surgery rate calculation could also be underestimated due to the lack of knowledge of patients’ history before 2015. In addition, because we only captured the records of hospitalisations during which surgery was performed, there are two circumstances of postoperative patient care: discharged at the same visit until full recovery; discharged shortly after surgery, home or transferred to other hospitals for postoperative care. In the latter case, since we were not able to make the linkage between surgery and rehabilitative stay, the LOS and costs of hospitalisation may be underestimated.