In the long-term treatment management of all chronic diseases, maintaining the efficacy of the treatment and monitoring side effects are critical. Therefore, CHB patients receiving treatment should undergo liver function tests once every 3 - 4 months in the first year and every 6 months thereafter. The serum HBV-DNA level should be examined once every 3 - 4 months in the first year and at 6- to 12-month intervals thereafter. When HBV DNA is not determined, the HBsAg and anti-HBs levels should be examined once every 12 months (
8). The CHB patients being followed up at 3-month intervals before the pandemic could not be seen for polyclinic checkups because of the COVID-19 pandemic restrictions. The right to be able to obtain the drugs without a prescription laid the foundation for these patients not to see the need to present at the polyclinic. This study showed that a negative effect should be considered on chronic diseases such as hepatitis b infection because of the extension of control visits during pandemics. The aim of this study was to evaluate the clinical, radiological (bone mineral densitometer), serological, biochemical, and molecular results of the patients who did not have polyclinic checkups.
Of the 220 patients who had checkups regularly before the pandemic, 142 (64.5%) had no checkup for approximately 2 years. Only 39 (17.7%) patients had regular checkups. Of the reasons given by the patients for not having checkups, the main reason was concern about COVID-19 infection. Another study reported that pregnant women did not have regular routine checkups during the pandemic as they felt uncomfortable (
9). In a study in Wuhan (China), it was seen that 41.9% of pregnant women refused to go to any hospital because of the fear of infection and would postpone antenatal care and admission to the hospital before birth (
10). Obstetricians in India reported that the most common concern of pregnant women was that they would contract the infection during hospital visits for antenatal checkups and ultrasounds (
11). It can be predicted that this situation would be seen more in CHB patients because most of these patients have no complaints. A previous study reported that one of the main reasons for not having a viral hepatitis test and accessing treatment was the fear of going to a health care facility because of COVID-19 (
12).
In the current study, 34 patients (who were young and mostly female) stopped treatment during the pandemic. In the patients who had been receiving antiviral treatment for a longer time, the rate of continuing to take the drugs was higher. It was thought that the importance of the disease could be better understood by those having checkups for a longer period. An interesting finding was that a significantly higher rate of patients with a family history of cirrhosis of the liver stopped treatment. The compliance to the treatment might be low because they may have believed that cirrhosis is the final inevitable outcome of CHB. It was observed that most patients who continued treatment had a COVID-19 vaccination, which was statistically significant. Due to the protection of the vaccination, it can be considered that the patients lost their concerns about COVID-19 and continued the treatment of CHB. These patients might have compliance with both their treatments and COVID-19 vaccinations. In the later stages of the pandemic (when there was an increase in COVID-19 vaccinations), a study conducted in Canada showed that with this effect, there was an increase in hospital presentations (
13).
HBsAg seroclearance and its conversion to an antibody against hepatitis B surface antigen (anti-HBs) is uncommon in chronic infections. In an Asian population, the annual incidence of HBsAg clearance was 0.33% - 5.0% with antiviral treatments and 0.5% - 2.66% without antiviral treatments (
14-
17). In a study in Turkey, HBsAg seroclearance was developed in only 2 of 173 HBeAg-negative patients, and anti-HBs seroconversion was not determined (
18). In the current study, HBsAg loss was seen in 1 patient who stopped treatment and in 2 patients who continued treatment, and anti-HBs seroconversion was developed in 2 patients who continued treatment. Similarly, HBeAg loss was observed in 1 patient who stopped treatment and in 2 patients who continued treatment, and anti-HBe seroconversion was developed in 2 patients who continued treatment. Seroconversion was developed more in patients who continued treatment, which is consistent with previous studies. However, the timing of seroconversion developed in patients who did not regularly have checkups could not be determined. It is recommended that treatment be continued for 1 more year after seroconversion (
8). As this timing was not clearly known, patients will have to remain in treatment for a longer period.
There are 2 formulations of tenofovir for the treatment of HBV: TDF and TAF. ETV is generally well tolerated in CHB. In patients with a high potential for side effects related to the bones and kidneys, it is recommended that treatment be changed from TDF to TAF or ETV (
8,
19,
20). Previous studies have reported that long-term use of TDF results in a decrease in BMD and an increase in renal toxicity (
20-
22). Patients who changed from TDF to TAF showed a significant improvement in estimated glomerular filtration rate (eGFR) levels and hip and spine T scores (
20). In another study, it was observed that after 2 years of TDF treatment, eGFR significantly decreased. In patients who received ETV, eGFR remained stable throughout 3 years and significantly improved after 4 and 5 years (
23). Consistent with previous studies, a decrease in eGFR was observed in patients who continued TDF treatment. Moreover, in 9 patients who continued to use TDF and had not been determined by proteinuria before the pandemic, the treatment was changed to ETV or TAF after the pandemic as proteinuria was determined. Previous studies have shown that proteinuria is one of the side effects seen in TDF regimens (
24,
25). When proteinuria develops in HBV patients using TDF, it is recommended that the treatment be changed to TAF or ETV (
6,
7,
26).
In the current study, the vertebra T score was found to be significantly higher after the pandemic than before the pandemic in patients who stopped treatment, as well as to be significantly lower in those who continued treatment. In addition to not being the only significant factor for the reduction in BMD, drugs seems to have a large effect on it. Both the vertebra T score and the femur T score were significantly lower after the pandemic than before the pandemic in the patients who continued TDF treatment. These results are consistent with previous studies (
20).
Of the 34 (15.5%) patients who stopped taking antiviral treatment during the pandemic, 20 (58.9%) were determined by HBV DNA < 2000 IU/mL and 14 (41.1%) with HBV DNA > 2000 IU/mL. Of those with HBV DNA < 2000 IU/mL, 6 did not wish to resume treatment, and in 2 of these patients, the result was negative. Acceptable treatment termination is stated in the guidelines as continuous virological improvement [HBV DNA levels were not determined by sensitive polymerase chain reaction (PCR)] (
5,
9). In a previous study of 504 HBeAg-negative, non-cirrhotic patients who were followed up without treatment for at least 30 months after previous ETV or TDF, virological recurrence was determined in 81 patients. Of these 81 patients, HBV DNA > 2000 IU/mL was determined in 52 patients, and following virological recurrence in 29 patients, a permanent virological dominance (HBV DNA < 2000 IU/mL) was seen at least 1.5 years later (
27). In another study, of the 250 patients for whom ETV was stopped, there was permanent virological dominance in 71 (28.4%) patients and virological recurrence in 35 (15%) patients. In patients who developed virological recurrence, clinical recurrence did not develop, or there was no need for treatment again (
28). Virological recurrence was determined at a higher rate in the current study than in the literature. In addition, a significant increase in the ALT value was determined in patients who stopped treatment. All guidelines state that normalization of ALT is an important factor in the follow-up of CHB and is a marker of biochemical response (
7,
25,
29). Such a result seen in patients who stopped treatment is supported by the guidelines.
5.1. Conclusion
The COVID-19 pandemic had negative effects on the follow-up of patients with chronic diseases. The most common reason for not having checkups was concerns about COVID-19 infection. The primary negative effects encountered in the follow-up of patients were biochemical impairment and virological recurrence developed as a result of stopping treatment. Following the use of TDF, a decrease was seen in BMD, a fall in the level of eGFR, and side effects such as proteinuria. Both HBsAg seroconversion and HBeAg seroconversion were observed more often in patients who continued treatment. To continue antiviral treatments and follow up side effects, patients should have regular checkups.